A few things:

I sold an '05 Bianchi with (9-speed 105's) for $750 two weeks ago. The market here is kinda high. I'd say shoot for $550, but if it fits and is in good shape you shouldn't walk away at $600.

Mileage that low is possible. Some folks have a couple other bikes, or a growing family, or other hobbies, or... I've seen a number of bikes that get 500 miles that first summer and then hang in the garage until they are sold 4-5 years later.

Good luck with your plan (no 'e').