I'm not sure where in Minnesota you live but I found some contact info on low cost spay/neuter programs in your state:

Spay, Neuter, Aid Program (SNAP)
Contented Critters
PO Box 385
Makinen, MN 55763
218-638-2153
Low cost spay/neuter for pets of qualified low income people.

Duluth Animal Allies Humane Society
& City of Duluth Animal Shelter
2627 Courtland St
Duluth, MN 55806
218-722-5341

Minnesota Spay/Neuter Project http://www.geocities.com/mnspayneuter/news.htm