About 99% of hiring field service firms do NOT require that the field service service representatives pay for a background check. It just doesn’t happen.
Be sure to ask UPFRONT about background checks. You do not want to waste a lot of your time filling out a long application form to find out that the firms wants YOU to pay for a background check.
I would make it a general rule to PASS on firms that require that you pay the fee. Be sure to ask UPFRONT.
Don’t start a trend.
Search the SOFI Blog (search window in upper right corner of home page) using the keywords background check to read a bunch of related posts.
SOFIBlog.com ... 352-324-6042 Florida 
There is one national Mortgage Inspection Firm that requires this (name not disclosed). I found out after applying and being “accepted.” Thankfully the application process wasn’t long and arduous. Of course once I saw that I had to pay the $35 fee I said forget it. That’s about an average cost unless said company subscribes to a service for unlimited checks, in which case the first handful or so pay for the month and the rest is pure profit.