On flatlandfuel.com:
Arestic Ice Metal Crank Euro 165mm (with bottom bracket)
List Price: $149.99
Sale Price: $104.99



http://obmx.com/itemdetails.cfm?id=3217&catalogId=150
PROFILE - MINI MAGNUTANIUM 3-PIECE CRANKS (138) $300.00 (with bottom bracket)


Keep a lookout for "Flatland" specific parts. BMX Flatlanders are weight weinies and run short crank arms starting at around 160mm (even down to 140mm).