Regarding the ledges, I would recommend some research on YouTube about how to make your own ledges. There is a lot of support out there for chinchillas specifically. The cheapest option is to make your own with hanger bolts and Wing nuts to secure them to the cage

As far as treats I would recommend ChinVilla on etsy. Both of my chins absolutely love the treat variation that they give and it's perfectly safe. This is also a great shop for chew toys and accessories as well. You can also make your own toys using seagrass twine or wire and little Willow balls, stars, and apple sticks, Timothy hay treats.

If you know how to sew, you can make your own hay feeder out of fleece and there are some tutorials available online for that as well.

There are two ways that you can go about flooring for your cage. I have tried both fleece and Aspen pine bedding and Aspen pine is way better. You don't have to clean as often and it will smell better as well. You can purchase a large bag on Amazon for pretty cheap.

As far as food you want to go with oxbow red bag of pellets and for hay I recommend this. Quality hay, my chins love it!

Feel free to ask as many questions as possible on here. There are a lot of well-educated people with lots of experience!