I have bought and sold hundreds of times on eBay. My purchases have been mostly small items under $100 - everything from CDs, old soda bottles, car parts, books, power tools. However, I bought my wife's car through eBay two months ago. Granted, the car happened to be located a mile from my workplace and I did drive it first.
The "pc crash" excuse is a cop out, plain and simple. Almost any mall has an ISP selling service at a kiosk where you can log on to any site you want. And let me guess, the guy doens't know anyone else with a PC - not likely. First, leave scathing feedback for the guy, second complain to eBay. Both may get you nowhere and you probably wouldn't want to buy from the guy anyhow but at least others will know his track record.
Anytime I buy, I check the feedback first. If someone left negative feedback, I check that persons feedback as well to see if he/she is just a whiner or what. As always it's buyer beware but I have only been burned once and I was able to resolve it.
My $.02.