Is Dry nitrous refill expensive?and Should I be able to get at local gas supplier?

 

it's going to cost you the same whether the kit is wet or dry. a dry kit only sprays in nitrous and you have to find a way to get more fuel into the engine to compensate which means spraying before the MAF. a wet kit sprays both nitrous and fuel out of the nozzle at the same time. lots of performance shops sell nitrous. i'd say find one or call them up and they can tell u where else to find it.