Unless you are trying to get a short notice reservation, there is no need for a certified check. If your check doesn't clear, the owner can just cancel the reservation.
Now if you are trying to get a reservation that is 60 days or less from now, I don't blame the owner one bit for wanting assurance that he/she will be paid.
As I hope you already know, the owner retains complete control of the
DVC reservation until you check in. He/She is the only one who can make changes, add the Dining Plan, Magical Express or room requests. He/She also has the ability to cancel the reservation completely, even though you have paid for the reservation.
But that said, out of the thousands and thousands and thousands of rental transactions completed via the DIS, less than a handful have reported fraud.
Most problems occur when either the owner or the prospective renter are new to renting and really don't quite know what they are doing. A low post count makes this a possibility. Good to see that you are doing your homework before blithely sending off your trust and money.
If you haven't already, ask lots of questions and make sure you are comfortable with this person before you send money. Ask for something in writing that describes the terms - that won't necessarily protect you from fraud, but it will absolutely help to make sure both parties are "on the same page". Be sure you understand the owner's policy on changes and cancellations. They vary between owners. Most will consider the transaction to be non-refundable.
Good luck - renting can be a tremendous bargain in the right circumstances.
