Yeah, it should work. Jo-Ann Fabrics, Hobby Lobby, and most craft stores will have HTV. Or if you can wait a few days you can also get HTV per foot several places online, and a few of them have free shipping.
Seiki 720T may run with the SignBlazer program using the Master/LiYu driver.
Nothing to lose, and if it doesn't, you can run through the list of units and try to find one that gets the cutter to work.