Those gemini scales suck ass and provide a false sense of accuracy by measuring 0.001g.
Anyone who doubts this should take it to your local hs or college and test it against their lab balances. They are way off.
I recommend the 0.01g scales. They are much more precise (you can measure the same thing 10 times and get the same measurement every time, as opposed to the wild variation in gemini). You can always split portions or do volumetric dosing if you need small measurements.
Personal fav https://www.amazon.com/dp/B07HGWFBTV/ref=cm_sw_r_oth_apip_wDIxlxR23ScWJ
Runner up https://www.amazon.com/dp/B0012LOQUQ/ref=cm_sw_r_oth_apip_NbsbhiB4NGRRK
I have 2 of these are fits fine as long as you detach the cover.
AWS Series Digital Pocket Weight... https://www.amazon.com/dp/B0012LOQUQ?ref=ppx_pop_mob_ap_share
The AWS LB-501 is a good scale. I bought one when I started making larger batches > 120ml. Prior to that I used the AWS-100 which can be had for $8.95. It is battery operated but the batteries last a long time. It does have an idle timeout of 60 seconds, but I just tested and as long as it's in use it doesn't time out. With that said, i never used it that way. Scales automatically tare when you you turn them on, so I just got in the habit of 1. Turn scale on, 2. Add ingredient, 3. Turn scale off. Not as convenient as always on, but honestly only one button press more than hitting tare on the LB-501 and helps the batteries last that much longer. It's also significantly smaller and not oddly shaped so easier to store than the LB-501. I can not recall if mine came with calibration weights, but those can be had cheaply enough that the total price should still stay around $20.
I found a $14 scale on Amazon through this sub. I'm a little anxious-leaning/neurotic so felt safer doing .01 below the already recommended lower .05 dose that some people say to start with. My scale was delivered in one day: https://www.amazon.com/American-Weigh-AWS-100-Digital-Resolution/dp/B0012LOQUQ
https://www.amazon.com/American-Weigh-Digital-Scale-sensitivity/dp/B0012LOQUQ
I have this one, highly recommend. Only downside is it turns off after like 30 seconds of not using it. That's what most of the negative reviews are about.
This is the jeweler scale: AWS Series Digital Pocket Weight Scale 100g x 0.01g, (Black), AWS-100-Black https://smile.amazon.com/dp/B0012LOQUQ/ref=cm_sw_r_cp_api_i_kIUhFbB1H1M5Y
That scale says 0.01oz which is very different from 0.01g (which is what you want). I use one of these.
edit: The scale I linked only goes up to 100g, so if you plan mixing large batches, like over 100ml, get something with a higher limit - I never mix over 60ml at a time so it's fine for me.
After navigating some of the recommendations, I got a laugh at the "Frequently Bought Together...Buy Both" recommendations.
http://www.amazon.com/American-Weigh-Signature-AWS-100-Digital/dp/B0012LOQUQ/ref=pd_bxgy_misc_text_y
Get the aws hundredth scale on amazon. It's like ten bucks.
Edit: link http://www.amazon.com/American-Weigh-0-01g-Digital-Scale/dp/B0012LOQUQ
Pretty easy to find on Amazon. I bought this one years ago and it works great. You might want to get a reference weight to calibrate as well but not required.
I was given this kit several years ago: http://www.amazon.com/Artistre-Molecular-Gastronomy-Experimental-Assortment/dp/B00OIC5KII . I greatly enjoyed it but some things aren't super useful to me and a customized kit would have been excellent
Suggestions:
a scale! http://www.amazon.com/American-Weigh-0-01g-Digital-Scale/dp/B0012LOQUQ/ref=sr_1_1?ie=UTF8&qid=1418959233&sr=8-1&keywords=american+weigh+scale is what I used to use, super cheap and mostly accurate (i suggest also buying a few calibration weights to make sure of that). If you want to spend a touch more get one with either a larger platform or a display that won't be covered but 0.01g resolution is really important. I use a lab scale now but I still have the AWS for when I'm traveling or for when I need a second scale. Most of these compounds are essentially useless without a scale though
anti static dishes are handy but not essential. However I love having them around http://www.amazon.com/Eagle-Thermoplastics-WB-158-100-Polystyrene-Anti-Static/dp/B00CQB5SFS/ref=sr_1_4?ie=UTF8&qid=1418959559&sr=8-4&keywords=anti+static+dish is an example, you can probably find cheaper (and could get away with less as you could wash with soap and water and be okay versus a lab that would just dispose them to avoid any chance of contamination)
2-4mL disposable pipettes are super cheap (think 5 bucks for 100+) and incredibly handy, especially for weighing small amounts of liquids and plating
as for additives and such; personally i would start with the easy yet dramatic results. N-Zorbit is just fun to use and gives really neat results quickly, sodium citrate for fancy cheese sauces, lecithin and xanthan gum to emulsify and thicken sauces, etc. It's hard to make other recommendations without knowing what he wants to do and what his interests are.
In terms of barbecue I don't use much, MSG for spice rubs if that counts and calcium silicate for an anti-caking agent when I make spice rubs in bulk. For sauces I sometimes use the modified starches to thicken; Ultratex because it's essentially flavorless or xanthan because it's effective in small amounts.
or just get a gift certificate for modernist pantry. they ship internationally and are very helpful. Willpowder also ships internationally but only to certain countries.