The Bandai kits are generally not hard to find for reasonable prices. Bigbadtoystore (among others) regularly adds new stock every few months. The trouble can be if you’re looking for a specific model and it’s been a while since they’ve done a production run of that particular kit, then the aftermarket prices can be high. But usually if you’re patient you’ll see another production run pop up.

The one kit I keep hoping to see restocked is the 1/12 speeder bike w/scout trooper. That one has been OOP for a few years now I think and is tough to find for a decent price.

The best advice is to find some reliable online retailers and keep an eye on their stock at least weekly. The popular kits can sell out fairly quick when they show up. Also, check hobby lobby (they usually have some Bandai kits, but the selection is very limited). And last, if you have any local hobby shops nearby, go scope them out. I’m lucky to have quite a few mom and pop type hobby shops in driving distance and I often see plenty of Star Wars kits for retail prices on their shelves. Including plenty that have become scarce online and command premiums if you do find them.

Oh, regarding size, check the scale of the model. It’s read as a fraction so the larger the second number is, the smaller the kit will be. (1:32 will be a fairly large model whereas 1:144 will be quite small. Basically 1:144 means it would take 144 copies of the model to add up to the length or width of a full “life sized” ship)