I normally agree with the upfront fee bit, but arise.com is one place that does require you to pay for your own background check and training upfront and is still legitimate.
Arise is legit. You work as an independent contractor so the pay isn't great, but the job is actually lots of fun and very flexible with your time. The same course will pop up at different prices at different times of year, so if you can bide your time you can catch at a discount.
I used to do similar work for Sykes Enterprises for a large tech company...it paid better but your hours were not flexible.