You may want to look at the "Market Place" on here. There was a Storm for sale that is a great deal. I have seen several eBay salers that looked trust worthy from looking at their feedback and length of saleing. I have also looked at a few Craigslist adds that I may trust only because I could go and see the phone + check on the ESN. As in any secondary purchase Cavet Emporer. Oh I bought my 8330 as a 2 month old used phone from a good bud that is/ was a Alltel autorized dealer.
If you use eBay, as long as you pay using PayPal, you are fairly well protected against fraudulent sellers.
Also, you can purchase a warranty on eBay bought phones by going to squaretrade.com. Their warranties are very reasonably priced. You won't be able to purchase any kind of warranty on BBs purchased on Craigslist or the CB marketplace.
Craigslist is great.. Some things to keep in mind.
1. Meet in a public area or the carriers store
2. Try to bring a friend
3. Don't be rushed
4. When you're the buyer, have your money set aside already
5. When you're the seller, CHECK your money on the spot.
6. If you feel fishy, get any vehicle info you can.
Personally, I've had no problems with buying and selling phones through craigslist, but there are people who are just out to scam you.
i would get it from the marketplace here before i go to craigslist or ebay. most of the phones available here are unlocked and well cared for and modded by BB fanatics as opposed to phones being ditched by soccor moms on ebay.