I have no problem buying used, but I didn't with the K2 because I didn't get enough of a discount out of it to make it worth the trouble. I'd say you should easily be able to get 10% off the list price plus a free cover from most people selling, but I'd hold out for a better deal than that. For me, $275-$300 with free cover would be a good price worth buying at, not more.
BTW my secret to buying used is not to shop on ebay, but to look on craigslist. Folks are willing to bargain on price there like they can't on ebay. If you search on google for
Kindle 2 site:craigslist.org you'll see everyone nationwide who is selling, then you just need to find someone willing to ship it. That's how I bought my original PRS-500 and several other items for less than what I could find it on ebay for.
NEVER PAY VIA WESTERN UNION OR ANYTHING BUT PAYPAL TO A VERIFIED USER.