Don't buy , it's free everywhere.
I bought lifetime ultimate access for like $100 when they launched it and then BC came out and I lost access to everything vanilla, which is all I played. Then they deleted my BC content, I emailed support and they just said too bad. I figured buying ultimate would give you everything but it gave me nothing useful... Would have been an easy fix if they weren't so greedy.
So sail the high seas on this one, and now I have everything again. Also pretty sure the "free" version works on Linux as that's what I usually run.