What voltages do you have to start with, and how good does the regulation need to be? (I imagine that for that, the regulation does not need to be good at all.) What I've done sometimes is to make an oscillator with decent output drive, even if that means a relaxation oscillator using a 5V schmitt-trigger inverter followed by the other five inverter sections in the hex inverter IC in parallel to provide more drive (74AC is strong, and 74ABT is even stronger), then follow those with a voltage multiplier with capacitors and Schottky diodes. It is compact and the efficiency is not bad. You probably won't even need to regulate it for your application.
Unfortunately switched-capacitor voltage-multiplier ICs won't work for the high voltage you need, and switching regulators are hardly in the hobbyist's reach because good board layout is so extremely critical to good operation, and you can't do it on prototyping board of any kind.
I do plan to put some power supply designs in my
circuit potpourri page of the
6502 primer, including this kind of thing. I also have a small module here that I made to start with anywhere from 7 to 17 volts (allowing a wide range of battery, wall-wart, and vehicle power) and put out +5V and ±12V that I wanted to supply to hobbyists but unfortunately it will be too labor-intensive for me to assemble it to sell without losing my shirt, and I know there won't be the sales volume to justify the expense of setting up for automated assembly.