Special months of discounts
I am not sure of the exact month, but there is a month of "discounts" on spaying/nuetering animals. The Humane Society may sponsor this. They usually offer good discounts for this service anyways. However, there is an even deeper discount at certain times of the year.
When I got my cat fixed it was $45 for that certain month. Our animal shelter makes it mandatory for the animals to be fixed prior to adoption. They actually do it BEFORE you can take the animal home. It is included in the adoption fee. So now it costs about $85 to adopt. Animals already fixed are cheaper.
For the redness issue... Could it be fleas? They can cause some redness in that area. Especially if she is chewing at it. The symptoms seem to come and go sproradically. May get some flea spray and spray her back end area.
Please make sure you can find a vet to do the fixing soon. There are programs out there. Make a few calls in the area or maybe look it up on the internet.