Can you burn there?
Are you trying to do this for little or no cost?
I suppose you could first try selling the trees. I don't know if they have any value or not? Pulpwood? Firewood? Other? Try looking for logging companies in the phone book. Wouldn't hurt to ask around.
Or if that poops out, so far as getting rid of the trees, perhaps you could hire a professional tree company to just fall the trees (very dangerous), then give away the wood. FREE FIREWOOD WOOD HERE -> Then burn the limbs if you can.
Wood is much safer to cut once it is down on the ground, but still can be dangerous if the limbs are still attached or logs are scattered here and there in piles. Safest is if logs are all in one stack aligned the same direction and the person cutting can easily pull logs out of the pile to cut on the ground.
The problem is if someone falls the trees and gets hurt on your property. Can any of the trees fall into your house, a fence, electric lines, underground lines, etc.? What if someone trys to fall a tree, it gets "hung-up" on another tree, then they leave it. Then some kid comes along and the tree falls on the kid? Lots of potential problems here!
Professional tree service companies know how to fall the trees safely, but they also charge a young fortune.
Logging companies know how to fall trees safely, but they would need to be able to sell the wood.
Maybe you could get someone from one of these companies who wants to do some side work on the weekends?
Another option is to get rid of a few trees a year as your budget allows. If you do this, you can get a cheap electric chainsaw to cut out the roots. This will damage the chain, but the chains for this are cheap as compared with paying someone to do the work. Or you can get a cheap chainsaw grinder and learn how to sharpen chainsaws.
Just throwing ideas out there...