Mullvad even gives you a 10% discount for bitcoin, bitcoin cash, and monero payments.
I am a bit disappointed that they haven't yet integrated bitcoin lightning network. That would be a huge improvement for reduced transaction fees given the low value of transactions they deal with, as well as instant confirmation rather than 6 block (~1 hour) confirmations. You could even theoretically stream nanopayments for each minute of use with lightning, rather than pay for a whole month.