What's the NADA book value on it for your zip code..... and for some reason in the midwest (ND, MN, WI, IA, WI, MI, ect) add $100-500 onto that!! :wtf:
If it is super clean, low miles and the rest of the property looked good/well kept.... I would pay the $3700. Now, on the other hand a new 2013-2014 Sportsman 400 (455cc & 5hp less then the 500cc) should be OTD for about $5200'ish. So the asking price for a 2006 (8 year old machine) for $4100 is a little silly when a brand new one can be had for $1000-1200 more. But a budget is and can be a budget!
When I was looking for our second machine (wife's) last year, I too found it funny how much used machines went for. Ended up with a super clean 2005 Sportsman 400 (425cc) in the color blue (was a search criteria of the wife's..... don't laugh!), #2500 Warn winch, brand new plow and a nice set of rims/tires for an asking price of $4700..... Ended up they were going on a Disney trip and wanted the coin, so I scored it for $4100 and sold the plow system for $300.... so basically $3700. And yes the property was very nice and clean/ well kept.... so you can assume all of his things are USUALLY!!
So long story short.... the 2006 Sportsman 500 EFI in MI for $3700, isn't too bad of deal. But a better deal may come along. But it sounds good to me if it all "checks out"!!
Good Luck!