|"No shop near me selling compressed air"|
Cans of compressed air can be purchased at a lot of different places, you do NOT have to go to a computer shop. I don't know if you're in the US or not, but you can buy it at Kmart, Walmart, Target, OfficeMax, BestBuy, drug stores, etc.
Ever hear of an air compressor or tire inflator? They will work too.