Poorkid,
Check with Dave Brown. He seems to know where us "common modelers" can buy an off the shelf jet that'll do 300 MPH.

"Those extremes could be handled within a "one membership fits all" policy, and there was little need to consider any other policy. Technology has not only made it possible to fly a greater cross section of models, it has made flying models over a much wider spectrum, practical, and popular. Who would have thought, 25 years ago that models capable of 300MPH would become available to the common modeler? Who would have thought that an RC model, weighing, but a few ounces, would be available to the average modeler, and have enough thrust to hover on it's electric motor, and fly for nearly 1/2 hour. Who would have thought of 50 Ib models, with enough power to accelerate, vertically. These are common place models, today, and what the future will bring is exciting to ponder."

Although I haven't seen one yet but they must be available, DB said so!. Oh wait, it's going 300 MPH, maybe THAT'S why I can't see it.
BRG,
Jon