I hope this doesn't come off as being rude...but if $160 is too expensive for you (and trust me, I know what that feels like after living off $7000/year these last 3 years..) I would recommend thinking twice getting a cat at all. What will happen if in needs emergency vet treatment? Even just a vet consults and antibiotics or x-rays are relatively expensive and owners who don't think their purchase through end up giving up their cat to the SPCA.
As others have said, $160 is a great price to pay for a cat who's has been checked, vaccinated, de-sexed and potentially more. With all the poor animals being put down every year, skimping out on de-sexing is just irresponsible.