When my son was around 9-12, he would want and buy Star Wars Lego sets with specific figures in them. He was well aware of the “rare” mini-figs, and could really care less about the sets otherwise. After awhile, he said that Lego was basically flooding the market by making more of the “rare” ones. If you have a young Lego lover in your world, they might be a great resource.
I found commercial wire “Eagle” brand shelves on Craigslist for $20 each from a shoe store going out of business. They are heavy duty and built to last. I actually bought 10, but several were “adopted” by my husband.