Bullets, the thourim ones, and mith ones before that, i realy cant think of anything that takes less mats than bullets, and gasp, they actualy sell ok, if your server is old enuff.
but explosives are also a good run.
Thorium Shells take 285 so you got 20 points to get their, but that should take ya though the end.
Thorium Grenade take a lot more mats, but you can run and throw at the same time, the stunn is amazing and you can start those today, once ya get to 285 hit up the AH and get the thorium shells schematic, and you are essentaly done,300 is just arround the corner.