my personal game storage is this:
https://www.target.com/p/5-shelf-bookcase-sauder-174/-/A-50364778#lnk=sametab&preselect=50300325they comfortably fit ~320 ps2 cases each but you have to get creative with the shelves themselves as there are only 3 and 1 unmovable one. I just remove a shelf from my more filled ones and use them for other games like cartridges.
at my local target they are also only $24 but it seems like every year or so they mess with the dimensions of the shelves. I have 5 of exactly the same ones but 3 different depths to them. one where I can comfortably double up the games, one where 3/4ths of a second case will overhang the end of the shelf, and one where there is only about 3 inches of room from the edge of the first case. I prefer the astetics of the last one but have found on carpet it is rather unstable as such I put lighter games on the top shelves, losser packed, and heavier ones, tighter packed, on the bottom.
I've been eyeing this shelf for a couple days now, but was wondering if anyone else knew if there were better options.
im not sure how big into collecting you are (if you will ever fill more than 1 bookcase) but the bottom of that unit will make it waste a lot of space if you ever buy a second one just because you can not butt them up together.