I actually think the bike is priced just fine. From what I can tell, the only 105 part is the rear derailleur. The drivetrain is otherwise nothing to necessarily highlight. The bike is 5 years old and, perhaps more importantly, probably one of many for sale in your area that are relatively similar, i.e., an entry level fitness/hybrid type bike. You're also nearing the end of the summer riding season so demand might be lower.

I would list it at $275 or best offer. If you get several people interested in it, then negotiate up from there or take $275 and run. You're likely not leaving that much more money on the table. Or list it higher and if you don't quickly get any interest, reduce it from there. Your call....