In prior years I've had good experiences with gunbroker.com buying and selling, but this year...sheesh!
I had two buyers win auctions for the same pistol* I listed but I let them off the hook (nice guy that I am) because they didn't realize how expensive shipping was (even though I wrote in the ad that shipping was prohibitive); I don't live near a reliable FFL so I'm forced--by postal standards and Gunbroker's rules--to ship handguns overnight through FedEx or UPS--they each wanted over $110 for shipping. My advice to buyers/bidders is to ask before you bid what the potential shipping charges will be to your locale/FFL.
After the third auction ended without a buyer, I got my bill from Gunbroker--they charged me for three separate listings (even though their relisting instructions don't mention that) and they billed me for tax for the unsold pistol! It was a terrible experience working with their Customer Service department** where it became so bad I contested the fees with my bank so my credit card was eventually credited.
I'll continue buying through Gunbroker, but as a seller...never again.
*I relisted it a total of three times.
**They'll only reply via terse e-mails; usually the first response is canned so you'll end up sending follow-up ones for specific answers. I got their phone number--which at the time was nowhere to be found on their website--through my bank when I contested their charges, but when I called I got an un-identified voicemail message; they never returned my calls.