As others have stated KBB and looking on EB and CL would be my choice...! I would then look at mileage and condition keeping focus on the eye of the prize. Do you want a "pristine" close to stock as possible for you to use as your daily driver...then I would probablly opt with a 2007 or later...! They have all the "whiz-bang" low maintainence stuff like EFI and "modern styling" if you like black...although their "custom" has plenty of alloy and chrome to make you smile. They also fixed the lousy fuse block location, sorted out fueling and yes, quieted the exhaust note so it is a pretty "respectable" street machine. Expect to pay somewhere in the neighborhood of $5-6k for a good deal (new 883's are close to MSRP is high at $10k), but if you look around like Breeze said, the buying season in SD is probably very good...
If you are looking at restoring or a 2nd bike, the 2004-2006 models were the "2nd" gen carbureted models which can be had in the $3-5k range, but the carb "art" if you will was well sorted out by then and really reliable machines. If you are into "hot rodding" or tuning, earlier model years in the 1980-2003 have plenty of aftermarket support to build it up to suit...and the $3k or so is about what you can expect, though the closer to stock it is the more likely you will have less trouble...JMHO. There is a some good information in the Self Help section regarding buying tips on that new/used bike you select.
