Dc-DC convereter for MPPT using perturb and observe algo

Hi.I am using dc-dc convereter for 50 w solar panel,12 v battery for MPPT using perturb and observe method.
will any body tell me which dc-dc convereter should i use.what should be its input output voltage range.If any one can provide me with the market name od convereter upto 10 dollars.thanks

The MPPT converters I've built, have been done with microcontrollers, and I written the firmware for it.

There must be an MPPT chip somewhere. But I'm sure it would still have to be connected to a micro-controller via serial bus of some sort.