Small & Mighty Organizations

Do any groups offer just sponsorship for spay and neuter of community and owned cats but not physically hold the clinics themselves? If so how did you setup your program? We have run a monthly clinic using our local humane society's surgical suite for 17 years for TNRTF based on financial donation only.  It is run by volunteers except we pay our vet an hourly rate. We wish to step back and possibly raise funding for sponsoring for those that need assistance with spay/neuter and utilize our humane society's low cost spay/neuter clinics. 

Any recommendations/suggestions/advice is appreciated!