You will need a base ARR whenever $20 (not sure if the Twitch Prime/Amazon Prime deal is still going), and for the cheapest options, start on PC with Shadowbringers basic for another $40. The ARR will at least allow you to login and work on your HUD. Now until SHB hits there will be some odd issues when playing on PC. I.E. won't be able to make Au Ra, it'll claim your EXP is locked at 50, it will not load into most expansion zones, exception being Shirogane.

Also, I'm doing this myself as well. And wow... I got this far into my response to realize we are on the same server...