It's much harder to duplicate a jet belt than a rocket belt. (For one thing, governments don't like cruise missile engines to be for sale.) Nevertheless, Richard Brown (among others) in the UK has been persevering. He's built a unique engine of his own design.
Mr. Brown has just posted video of his flight tests, which employ a multi-axis rig that limits the trouble he can get into.
Mr. Brown has also written a good account of his device's development.