Well, I have some canine/vulpine type tails left over from Rainfurrest. I've been asking $40 for 'em. Although I'd have to dig out the box and see what colors I actually still have. I know I have the rust one near the middle, but I'm not sure about the rest.
If those don't suit you, you could try asking on the fursuitauctions livejournal, lots of people there selling things and taking commissions. (I take tail commissions too, but I'm full up for several months right now.)