You know nothing about Sun servers? Very well, then. I have one for sale that is very cheap - only $8,000 for you because you use this forum.
Actually, you can get an Ultra5 with 256MB RAM and 9GB storage for just a few hundred (monitor costs more). They're sold quite frequently on eBay.
SPARC's are dogs; Ultra is a different architecture (better). You need 128 to install and run 8i (this is the absolute minimum - the installer will fail if you have less than 128). If you are going to use Forms, you need 256MB for decent performance.
With an Ultra5, you can do pretty much everything you need to do as far as installation, configuration, testing, and using are concerned.