Fellow tall guy here. Honestly, if you're going to spend $200, I'd recommend getting a squat stand/cage. You can find a cheap squat stand for $130-250 (for example), or a cage for about $300. They're generally going to be more stable that the power tower you're looking at, and you can also use them for other things, like squats, if you have a barbell or think you might want to get one in the future, or for hanging your rings, etc.
Hey man I'm really sorry to hear about your neck pain. I know how chronic pain can just suck the life right out of you and make you want to give up. It's definitely not easy to keep going.
Can I ask what kind of work you do? I'm gonna assume you work in an office since you said you have to look down for certain things no matter what. I can relate with you not knowing how to hold your head/chin when looking down at things. I remember my neck feeling incredibly stiff and tense when I first made an effort to stay upright. The biggest thing that helped me was to not overthink it though.
For example, if I was at school and I had to take an exam, I found that allowing my body to do what felt comfortable was actually the best thing for the stiffness. For a while, I tried to look down at things with my eyes (which can be good advice depending on what exactly you're looking at) while keeping my neck in its neutral position, but especially with an office job and school, sometimes you just can't avoid it. Try to examine your coworkers and evaluate their posture in your head. If there's someone in your workplace who has good posture, watch how they hold their heads while looking down at things. I know it sounds a little silly, but especially if you've had bad posture your entire life, even simple things like looking down at something can seem foreign and awkward. Your body just isn't used to it yet. Another thing to note is that your neck, like any other part of your body, needs to be stretched and used. While looking down at something for extended periods of time is awful for the health of your neck, (e.g. looking down at a textbook or having your monitor positioned too low) you definitely can't neglect those muscles that allow you to look down. What I'm saying is, try to find a balance. Keep good posture in the back of your mind at all times, but if you have to momentarily look down at a document or something for work, do it. Don't overthink it, but be aware of the damage that poor posture can cause in the long term. I know it's hard, but it will get easier with time.
Some things that can help you:
If you think you have bad posture, look up these terms "upper-crossed syndrome", "rounded shoulders" and "forward head posture." There are a lot of helpful YouTube videos on how to fix these things at home.
I'm glad my post put some fire in you. Please don't give up. I know it can be difficult, but try your best.
P.S. Yes, hanging on a pull-up bar feels amazing. It's actually an exercise that's both easy to do and can help correct your posture. You can buy a cheap one on Amazon (~$30) that mounts on your doorway if you think it will fit. If not, I would recommend a cheap power rack (no more than $150) that has a pull-up built into it. This is the one that I bought for ~$130 if you're interested.
https://www.amazon.com/gp/product/B00HYQP72O/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Nothing beats a real pull up. Get a pull up tower. I have this one which is I used in an apartment, and it works great:
stands: depends on what you're looking for but you can get something like this (http://www.amazon.com/Barbell-Power-Rack-Exercise-Stand/dp/B00HYQP72O/) or the PowerLine one on amazon in the $150 range. they will work well enough but the best non-width adjustable are from Rogue and the best width adjustable are from IronMind. They definitely cost more though.
Bars: I like Eleiko if you have unlimited $ and Rogue WLing bearing bar if you're cool with $525. I haven't tried it yet but I think the Klokov bar is the best option sub $500 for WLing from what I've been told. But it isn't as good as the Rogue bar, as far as I can tell, so the $200 extra is better.
Weights, depends if you want full color kg or something random. But I think all of the Eleiko, Rogue, Pendlay, etc is all pretty similar Chinese stuff. Places like RepFitness are mildly cheaper (sometimes, depends on sales and such). The best option above those plates ($800-$1200/140kg) is the Uesaka Varsity Series which can be pieced together for something like $1300 for 140kg. And Uesaka makes the best bumper plates in the world in my opinion, they are bulletproof.
For wraps/straps, I am biased but we sell really good wrist wraps on hookgrip for $15/pair. I don't think there are better WLing wrist wraps unless you're just really partial to another style of wrap. The other good option would be everlast boxing hand wraps which are super cheap and are used by tons of high level lifters. Also, the straps we sell (the same ones Average Broz sells) are definitely the best, I've tried a ton of them and I haven't found anything better for WLing. Ironmind are good too but, for me, the way they are sewn is a little goofy and the nylon is too wide.
Belts... good question. Frankly I think there isn't a good standout WLing belt right now. We are in the process of getting an awesome belt in the hookgrip store but it's still a little while out. The valeo are good on amazon for velcro but really all the leather belts out there are pretty similar/bad in my opinion -- as far as WLing goes. If you want it just for squatting, there are some good options.
Shoes, just Rogue. Romaleos or Adipowers, best option is Rogue. Or you can do something like eastbay if you have a coupon to save some $.
How about this one? https://www.amazon.com/Barbell-Power-Rack-Exercise-Stand/dp/B00HYQP72O/ref=sxin_8_osp99-04b3bfe1_cov?ascsubtag=04b3bfe1-0003-4d56-8be2-8a34bfb0cc59&creativeASIN=B00HYQP72O&cv_ct_id=amzn1.osp.04b3bfe1-0003-4d56-8be2-8a34bfb0cc59&cv_ct_pg=search&cv_ct_wn=osp-search&keywords=bench+press&linkCode=oas&pd_rd_i=B00HYQP72O&pd_rd_r=fcf65e94-36ed-485c-befe-89cd13e402d0&pd_rd_w=E9yVq&pd_rd_wg=pi3LY&pf_rd_p=53eff971-6e12-4016-9864-b6dfd929b2b3&pf_rd_r=WSJM63WBT7CAT3H5V6FK&qid=1570405257&tag=gearpublish-20 its a little cheaper. How can I do dips though?
It's not the best power rack but...
At $89 you gotta get it. It's almost worth the price just as a strict pullup bar.
I got this barbell power rack. I hang my rings from it and can do every rings exercise I need.
https://www.amazon.com/CAP-Barbell-Power-Exercise-Stand/dp/B00HYQP72O?