Besides the other advice given, try checking into your state's Aging and Disability Services Administration. I'm not sure if all states provide the same services, but they may be able to help you get respite at a reduced cost. My mom and I had to go through a few respite workers until we found one that "fit", but it was worth it.
I've stuck with one caregiver, but I'm lucky enough to supplement that with family in the area. I think you'll have to decide what meets your needs best once you find out what resources are available to you.
Best of luck to you.