Just use any old case and an angle grinder.
You can easily "modify" them in unter 10 minutes.

I've been using a Cooler Master HAF XB Evo. While a very large cube case, it the sides and top are easily removable and it has fairly good access to the components. Probably not an ideal test bench but it is what I had on hand.

Hi, this image doesn't display.

See here for my procedure for posting from Google Photos:
Re: Televideo Telewave Audio 32 sound card, questions about its onboard wavetable ROM

not cheap, but small 😀 Streacom BC1
https://youtu.be/z-liULfh4CI?t=135

i tried to simulate with at boards: the asus tx97 and the gx4 486 vlb