2.89% service fee; about what you can by miles direct from airlines, except here you would have no quantity limitations.
For a J award seat US-Europe that averages 80K miles, your hard cost using this website service would be $2320 plus tax, not too shabby.
For a J award seat US-Asia that averages 100K miles, your hard cost using this website service would be $2890 plus tax, not so bad either.
I actually reserached this concept about a year ago, but couldn't get a any merchant vendor companies to bite. Congrats to the gent who made this fly!