Fees for each celebrity are negotiated on a case-by-case basis, but costs range from £300 - £5,000 for a dinner, depending on the celebrity (assuming that a dinner sitting will last one and a half hours). The fee does not include travel expenses incurred by the guest (which need to be reimbursed separately).
The email address provided is a Hotmail address, which screams "HOAX", but who knows? I haven't seen any reports debunking these guys, so they might well be for real.
