3.3V Voltage Regulator for LiPol battery
Texas Instruments has a great step-down DC/DC converter which operates from a Single Li-Ion Cell (3 V to 5.5 V). It is the LM3281.

Main features:


Operates from a Single Li-Ion Cell (3 V to 5.5 V)
6-MHz (typ.) PWM Switching Frequency
Fixed Output Voltage: 3.3 V
Up to 1.2-A Maximum Load Capability
High Efficiency: 94% (typ.) with 3.8-V VIN at 300 mA
Analog Bypass: 60-mV (typ.) Drop-Out at 600 mA






It is 0.861USD at a quantity of 10 at DigiKey or you can give a try and order samples from TI with an appropriate e-mail address.

A disadvtage in your case:


The only available packaging is BGA, but it has only six pins in two row on both side of the IC. So it is not impossible to solder it with a hot air soldering iron.