Before you spend $400 for a refurbed 6401, buy a new one for less than $500 from Baileys, site sponsor. Shipping free, because over $200, comes with a 20" bar and chain. REJ2
Is free shipping over $200 back on? I don't see it on the site.
To the OP - You can save money or you can save time, but probably not both.
I got one of my Stihl 660 powerheads off ebay last January for $510.
Probably more saw than you want to carry, and just got a 32" B&C from Bailey's for $55.
Another member just sold a running 660 here for $475. So $500 lets in a wide range of saws.
Right now thru February used saws will probably be going fairly cheap. Prices start rising again as we get to spring and just before Christmas peak.
Get yourself a compression tester and screwdrivers/torx wrenches so you can pull the muffler and go the CL route.
Since it doesn't sound like you plan on relying on your saw to work you should be able to easily get one or two good saws off CL for $500. And since you will be carrying it in and out I'd suggest you go for anything you can carry in your cart with a load of wood.
Now for the shameless plug - You probably run across some nice trees. Think of getting a Chain Saw Mill and carting out lumber instead of just firewood. Visit the milling forum
http://www.arboristsite.com/milling-saw-mills/ , when you make lumber there is a lot of wood left over for firewood. And there are often beautiful spalted pieces of lumber hiding in downed trees.