Barter. Trade something of value to an appraiser in return for the appraisal.
You can get a CMA from a real estate agent. That's good, but it's not an appraisal.
Still, why do you need an appraisal? If you're selling, the seller will pay for that when applying for a loan. If you're refinancing, you'll pay but generally most of the expenses can (if you wish) be rolled into the new loan. It's pretty unusual for a homeowner to want or need an appraisal.