those are highly limited and inefficient transactions and not a good indicator. VEry VERY often the phones that are listed early are not available early.
The way to look at valid comparable ebay prices is reputable seller one month at least after launch. Before launch you can find people listing them for any almost arbitrary amount and it doesn't mean there are complete and delivered sales.
So when you say you saw EVO on ebay early, the people who bought those may have gotten their phoens two weeks after someone going into a store. plus there is a an irrational premium in the first week.
IMHO You want to know the actual NIB, activated once but not used, reputable (99% or above) seller price on ebay averaged from at least 10 sales that were delivered (a couple of weeks after sale completion) to get an accurate secondary price on handsets.
As far as craigslist, I could advertise a NEW Epic last week for $100 or $1000 and what would that mean? there is no feedback method and almost no fraud protection.