Depending on what they're doing, some devs may consider lower FW consoles more valuable than others.
My opinion is (regardless if it's 3.15, 4.05, 4.55, 5.05, etc) if it's jailbreakable then you probably can get a bit more than what new consoles are currently going for.
There's always a chance if you list it in an auction and someone really wants it they'll pay a premium, but to the average user who wants to use it for hacks, mods, homebrew, etc I'd be surprised if it fetched more than $100 above the retail cost of a new console... unless you included additional accessories, games, etc perhaps.
Thanks guys. Game stop is offering $200 but it's a store credit. I looked at ebay & CL but prices vary and no mention of what firmware they are on. Maybe I'll toss it on fleabay this weekend and see what happens.