It gets kinda old in the late game, but it is still worth some money. I wouldn't drop more than $10 on it, and even then I'd do so a little reluctantly because of the devs.
You could hold for another Steam sale on it, but that might not happen. They had it for $7.50.
GameStop might still have it on their PC racks. I think they've got it down to $5. Good luck though.
Really, that's about all I can think of.