Well, the first question will be: What did you pay for it? Your dealer may already have stuck it to you if you paid above the market price on your first purchase, and what he's offering now could be a pretty good deal.
Let's look at some data.
An Orion 5 currently lists for $3700. That was probably a few hundred less in 2000 since Alembic has had a price increase since that bass was built. As such, a great deal on it new would have been in the vicinity of $2000, and a likely price under $2500.
Epics are much more common than Orions, and are pretty similar in features. If we look at eBay numbers, most Epics sell on the used market closer to $1000 than to $1500. In fact, the current eBay history shows no Epic with a bid over $1000. Personally, I like the Orion shape and balance a bit more and would pay a slightly higher price for one, but I am not in the market.
Regardless of how much you personally value your instrument, I would suspect that you can get about $1000 for it on a quick sale. You might get as much as $1500 from the right buyer if you're not in a hurry, and anything over $1200 would seem to be a pretty good price. At least that's my opinion based on what I see. Half of what you paid for it new is probably not awful considering the price they seem to be selling for.
Good luck!
-Bob
