You'll pay for it, though. Truly industrial-grade SD cards (i.e. SLC flash, industrial temperature range, specified terabytes written/MTBF) apparently cost over $10/GB unless you're buying in huge quantities. I guess that might be a good motivation to slim down your root filesystem.
A lot of the newer industrial cards are 'aMLC', which basically means you take an MLC NAND, but only stuff 11 or 00 into a cell and sort of treat it as SLC. You can get for close to $1/GB at sane quantities.
