Yes they do spay/neutering the price I don't know. But I do remember seeing that it was low cost and if you found your pet on the street they will do it for free
See Brian answer for prices. As someone who recently priced a few option - Seattle Humane was by far the cheepest and was one of the most professional as well. You'll need to make plans to drop your pet off for the day. I would recommend going ahead and opting for the extras too. Their price to get your pet chipped is also one of the best.
The cat neuter/spay is $30-45 depending on gender (boys are always cheaper). Dogs at $75-95.
Thanks! Your answer is awaiting moderation.