only 23? thats pretty simple: deans, 11.1v lipo, and mosfet for reliability sake.
but if you want a solid 30 or more:
$8-lower spring (m110 or m100 depending on what you want)
$20-SHS 13:1 gears
$30-SHS HS motor
$5-deans
$10-11.1v lipo or 7.4v depending on the ROF you're looking for
$30-MOSFET (I know the DE and infected ones are good)
$0-DIY mods (correct AoE, get good compression, etc..)