You might give Island Marine Salvage a call.One of the guys I work with talks highly of them,although I havent dealt with them myself.503-366-0823 They are over at Deer Island.By St helens,

They run an ad in the Nickel regularly.They have used and rebuilds from what I understand.
Good luck in your search.If you buy used check it out thouroly or have a mechanic do it.Watch thos motors that have had a lot of salt water usage.Its usually pretty easy to tell
Just had a 115 merc rebuilt,cost about $3200 with about $600 towards power packs and stator>not Cheap.Seen powerheads on the internet in the range your talking for $3200Then count on more $ for assembly and carb work etc,Just wanted to give you an idea of the $ signs on some of your options.In case you didnt know.I'm sure they could vary a lot though