I wasn't really serious, just musing. Now I'm musing harder, but still not really serious. For now. (Insulated pressure tank, electric heater with power from GSE, safety vent, dump valve, nozzle. Hmmm.)
More than 10 years ago (15 years?) I read the web site of a guy in Mexico who was selling it in gallon quantities, and selling rigs to make your own by starting with a 35% solution, which is not so hard to get. He said that it's really not so hard if you just make sure that the rig is 1) made completely of glass, and 2) scrupulously clean. He had pictures and video of, among other things, his daughter riding a rocket powered bicycle.
One can take HTP further in rocketry than monopropellant, but I guess any more said than that belongs in the research forum.