Hi,
Since the topic is in the "Professional Hardware and Electronics Design" Section, I wasn't thinking of some circuit hacking... We could discuss your "hard to solder" point, but I think that in general it should not be a problem to solder an SOIC or a TQFP, we do that on milled test-PCBs all the time.(Though a nice PCB with solder mask etc. is a great help). But if you're not used to it you might have problems...
Otherwise a nice idea, you'll maybe have to spend some thoughts on stability. OTOH, a DC/DC converter gives you a lot more functionality (over current protection, over temperature protection, fast FET drivers, etc.), but basically they are nearly the same circuit as you proposed, only with some additions. The cheapest parts I could find are from Texas Instruments a little more then 1$, which is indeed more then your solution will cost.
In the end it all depends on your needs/your application, which variant to choose...
You might also get along with some voltage doubling circuits and regulation afterwards, depending what you can do with your sensing circuits afterwards.
As I said, like most of the time, which solution is right highly depends on your needs/your application.
Regards,
Andreas