Termite treatment options
You said both contractors "think" you have termites. They should know and be able to point out evidence like Tester101 pointed out. Both prices seem high for just basically spraying, especially since you don't have a slab that has to be drilled through. Near the front door, they could have just came in under the door.  If they are subterranean, their should be evidence of how they got in - typically mud trails coming up from dirt, up the piers and into the house. They can also look for any things that are conducive to attracting them, such as any boards (pressure treated or not) that are in contact with both the house and the dirt. Just because you have seen a few doesn't mean they are already in your walls. A less expensive spraying might take care of it. I would call another guy and see what he thinks.