It's easier and cheaper to buy a few of those chineese "solar powered garden lamps" and rip them apart.
They cost about USD 8 retail and have a solar cell panel capable of 20 mA at
4 Volts, two 600 mAh NiMh batteries, a controller circuit and a white LED. Note the 20 mA, double what you get by stepping your voltage up ten times.I haven't been able to locate the source for the solar panel - I have a neat application for it, especially since the price for that panel must be below USD 2 for that lamp to be profitable, but no luck yet.
Maybe I should post some pictures??