I've just ordered one from a seller on ebay for £14, I suspect it might be coming from China despite being listed as 'UK seller', I'll let you know if it arrives.
I have a Gateway 2000 desktop computer that I bought in '98 too. Still going strong, despite multiple modifications and loads of house moves over the years. I has a 12Gb hard drive and a Pentium 3 450mhz processor. Slow as a wet week but I can't kill it!!