I don't think you have their business model right. They don't "buy" timeshares. I believe that you pay for the privilege of having them dump it on eBay for you and they keep the proceeds while you pay them $3000 for that privilege.
You may save yourself $3000 by posting on the TUG clasifieds area where you can give away your timeshare for free.
You can dump your timeshare on eBay, too. Just offer it for $1 plus closing plus maitenance fee reimbursement for this year's fees.
Do a search for Timeshare Relief. There are a few very long threads on this topic.