I sold my 2000 Scotts mower w/bagger last summer for $600 and I was surprised to get that. It was in very good shape but it certainly didn't have a new motor. I would have taken $450.
Check you local Craigs list for a reference on mower prices in your area. I believe you can get a bagger at a John Deere dealer, at least that's where I got new bags for mine. It is a pricey add on though. I would probably just look for a used one with bagger.
14 HP would be a little small IMHO. I had 17.5 HP and if the grass was a little long it would struggle.
Good Luck.