Actually 386 and 486 boards are getting rarer lately, and people on ebay are selling them for ridiculous prices to robotics and electronics experimenters.
Are there people dumb enough to be buying them, Steven?
And since, AFAIK, there are no chipsets that allow 386 or 486 processors to access modern RAM, a 4GB 386 or 486 combination is virtually impossible (as well as being pointless and extremely silly).