Best place to sell a bass right now? Try a different planet w/a functional economy!
I've had good luck here and on Craigslist. The keys to using CL effectively are:
1) Do your research for what comparable instruments actually sell for here, BassGear.com, Harmony Central, eBay etc. Know your rock-bottom price (but make sure it's realistic)!
2) Have good pix and as much information on specs/condition as possible (weight, scale length, dings/issues, repairs, modifications, what all the knobs/switches do). Linking to the manufacturer's pages is helpful. Tell people why you're selling up front.
3) State your terms. I always go for a firm price on CL and state cash only, no shipping, in person, serious inquiries only. Don't even respond to somebody who answers your ad and asks for different terms or price. I don't play games and won't tolerate people who do.
4) Give a phone # you check frequently. Tell people when they can reach you, and when you can show them the gear. Ask them to reply with a phone # and a good time for them to talk/check out gear.
5) If you're selling multiple items, price them separately (unless you're truly giving a ridiculous package deal) and consider separate ads.
In short: Know your lowest price. Give as much information as possible in the ad/pix/links. In my experience, the fewer times you go back & forth with little bits of info, the more likely you are to actually sell the thing. Tell people when/how to reach you, and ask them for same. Don't be afraid to walk away from a sketchy person or haggler. 95% of the people posting gear for sale on CL don't know *** they're doing and post the same overpriced crap for weeks/months on end.
I've sold quite a few things (including boutique basses) this way in the last year on the SF Bay CL within a week of posting the ad, and have always gotten my asking price. Usually the person who buys it is the first one to check it out--they don't want to miss out on a good deal.