If your looking for a normal PC case that can house some hardware but does not take up too much space I'd recommend the Dell Optiplex 990 case.
I converted an old server into my daily driver/gaming machine. Comfortably fits an Nvidia 1050TI and several SSD's while not taking up too much desk space. It's just a normal looking PC case, no fancy rainbow lights or anything.
Pics are not mine but are the case I'm talking about..
Building your own is probably going to be your best bet. With your budget you should be able to build a pretty kick ass machine that will keep up for quite a few years.