When I did SAR, I carried the heaviest-duty versions of my usual hiking gear (i.e. Leatherman over a tiny SAK, Cordura rucksack rather than a sil-nylon backpack). Tough clothes were a must, since bashing through briers and brush was part of every search around here. The only additional expense (thing I didn't have in the closet) was for a few minor required items like leather gloves, 20' of nylon webbing, and 2 locking 'biners.