Little pricing error going on over at Steam.
Seasons 2 and 5 were marked down 50% to $15 at the start of the sale. Thought about grabbing 5 then.
Just went back again, and at some point, season 5's base price got knocked down to $15. Just grabbed it half off for $7.50.
Same-ish with the pro pack if you prefer. Base price got dropped to $20. Currently on sale for $10.
Edit - Holy Hell I had forgotten how awful the interface was. Hadn't bought tables since season 4, rarely played since the DX11 update, nor played at all since June or so. What a shit show Farsight is. I used to play this a LOT. 100s of hours on Steam. I think this is getting relegated to "good for learning a table's rules" only for here on out. I'm not masochistic enough to play this for fun.