I wanted to try an idea appearing in Electronic Design (May 10 07) calling for an NTE 103 (TO5 NPN Ge)
They claim a DC/DC converter that will unconditionally start oscillating at ~260 millivolts.
It is a basic Eccles/Jordan flip flop with inductors in place of load resistors for voltage boost. They take output from both sides of the flip flop for higher current and low ripple. They also give a suggestion for using a JFET to turn it off (providing you have the voltage to do it).
Most of what I see for prices are in the $5-7 each for germanium transistors and the basic oscillator takes a pair of them - which prices them out for the numbers I was thinking.
NPN Ic of 100 ma to 500 ma, gain of ~100, 30 volt standoff would work.
PNP would also work but somewhat less desirable.