My 1988 Miyata 215st touring bike cost me $300+ new. It isn't "immaculate", but very nearly so. I don't think I'd have a problem getting $200 for it, and were I to sell it I'd start it off at $300 to see if I got lucky. I have another "like new" 215st that I would not take less than $300 for.
But, I live in a hot bike market and tourng bikes command a premium. Still, I'll bet a 310 sold in the $300 range ( and I further bet T-Mar will know
), and if it is immaculate - as in like new - $250 might be a fair price. Especially if it fits you and rocks your world.
Offer $200 and see if he gets insulted....
"Love is not the dying moan of a distant violin, itís the triumphant twang of a bedspring."
S. J. Perelman