Hydro-formed "Escopette"-style valveless pulsejet?
They run as efficiently as a turbojet (w.r.t. specific fuel consumption), and Mach 0.7 is way beyond your "couple hundred miles an hour".
It will be burnt up by the time it runs out of fuel, though.
For a good one it has to be hydro-formed out of seamless pipe, which is likely hot-stretched (like wire drawing, but using an induction heating coil in place of the die, and independently controlling the feed-rate and the pull-rate) in advance to retain consistent wall thickness in the engine despite being cross-section after hydro-forming. Also probably incremental hydro-forming with grain-structure-fixing re-heating between stages.
The hard part is just that most of the work is in making the hydro-forming dies/tools, not then using them to cheaply produce more engines.
Fascinating, haven't heard of this. Some googling suggested there is some active research in this area, and at least some active use by hobbyists and by the military in target drones. Seems like a promising angle for a cheaper cruise missile, at least on the engine front.
You're going to have serious troubles implementing a cruise missile with a range in the hundreds of miles with a solid rocket engine. While most cruise missiles use a solid booster to launch the missile and get it up to the proper speed and altitude, you need an engine to sustain flight. You also need a propulsion mechanism that allows you to control thrust, which a solid engine wouldn't. To my knowledge there is no cruise missile in existence that uses just a solid rocket engine. In theory you could get into the hundreds of miles with just a booster if you use it to get up to a significant altitude and glide the rest of the way. But that largely defeats the purpose of a cruise missile: traveling at low altitude to avoid enemy radar.
Of course, you can definitely make a BALLISTIC missile with a couple hundred mile range using a solid rocket engine, and probably for fairly cheap (especially if you don't particularly care about accuracy)
Also: Scud missiles are comparable, made outside western cost inflation, and still ~$1M each. So I'm guessing you can't get a ballistic missile anywhere near $10k (at least, not one that isn't more likely to kill its owner).
