It is more expensive to spay a cat who is either in heat or who is already pregnant. At the time of writing (February, 2013), I decided to call up 5 local (Australian) veterinary practices to find out how much they charge to spay a female cat.The prices ranged from $195.00 to $250.00, with an average cost of $223.80.t is more expensive to spay a cat who is either in heat or who is already pregnant. At the time of writing (February, 2013), I decided to call up 5 local (Australian) veterinary practices to find out how much they charge to spay a female cat.