If the instrument has been played in the shop for a couple of years and nobody's buying, perhaps it is not priced reasonably/competitively to start with. On the other hand, if "a little love" would make the instrument shine (and assuming it's the instrument you want), then why not buy it, give it a little love and MAKE it shine!
If a pristine instrument is important to you... why not offer to buy the same instrument new THROUGH that dealer who has made the trial experiences available to you?
Regardless, spend some time doing a little research... the internet makes it possible to compare prices of instruments, new and used, that are sold by other retailers, on ebay, and here in the classifieds. So it's not hard to find out what the "ballpark" range is out there on the market. Remember, also, to factor in the good karma of supporting your local retailer, the relationship you might like to have with them in the future, etc. And find out if they would give the instrument a once-over (clean it up, perhaps also a setup) as part of the sale.
Finally, I"d say that with $2k to spend on a good A mandolin, you have a lot of choices. IMHO, your energy is probably better spent at this point in figuring out which mando you want and why, rather than looking for the best deal.
Otter OM #1
Brian Dean OM #32
Old Wave Mandola #372
Phoenix Neoclassical #256
If you're gonna walk on thin ice, you might as well dance!