EPROM emulators are fairly complex, that one is only 32kB (maybe 64kB also, but the description sounds confusing). If you're gonna build one, you might as well go for 512kB or as much memory as you want.

I bought one to save time, but before then I was looking at building one like this:
http://www.devrs.com/e/tools.php

Except on there, there's 4 128kB RAM chips, which seems kinda pointless when you can just use one 512kB one instead.