Always go bigger for pow, some people like 180 cm boards for pow.
that being said The Capita Charlie Slasher and the Salomon Powder Snake are two of the cheapest pow deck out there. I have a charlie slasher 158 and im 180 lbs, i really wish i had gone with the 161 or 164.
another option is to get a huge (165 or bigger) older camber board and make it into a swallowtail. just google DIY swallowtail.
Dude, suckin at somethin' is just the first step to bein' sorta good at somethin'