Often when you are talking about barns and you will not be re-erecting it as it was, in other words just reclaiming the materials, you probably ideally want an even swap for the labor to take it down. It all depends on what the material value is. Large hardwood timbers, particularly good condition, or very large pine timbers play a positive role in being more valued. Typical salvage value of pine material(not particulary huge), without any labor needed, might be $.25/BDFT up to $3/BDFT. Personally I've tried to find reclaim timbers at .60/BDFT and under, and with careful looking, I've found some success. I buy at that rate so that I can afford to transport, resaw, or refinish them and still be at or less than $1.30 when I'm done. This provides enough savings to make the rework and effort worthwhile and still have a savings over buying new. $.80 or $1 is not uncommon by any means. These are all sawn timbers. Hewn timbers on the other hand tend to go much higher due to the look of them. It took a lot of hand work to hew them originally too, so you can't just buy them from a mill.
Back to your frame... It all depends. If you find someone who wants to use your exact frame, you may be able to trade them the frame for their labor to take it down plus have them separate the waste and fill your dumpsters with the junk debris(leave your site clean). I see barn frames for sale on ebay for big dollars($12K-$30K), but I don't know if many of them actually sell. It would seem like buying an existing frame would be like buying a newly cut one, but it is likely to need some work for anything that is not square or plum from damage over time. A picture of your frame would also help people here assess it. Is it currently an internally exposed frame or is it hidden within walls?
It's not uncommon for sills to be water damaged. Most frames people advertise do not include the sills becuase of that fact. You could use new sill timbers or provide for a conventional floor deck or rest the posts on concrete footings....This has been what I've seen over the last year and a half since venturing into timberframing.
