Right now it's going for $20 on Impulse.
http://www.impulsedriven.com/kingsbounty
I would avoid buying on Steam like the plague. This particular game seems to completely break when moving between some versions. Some are unstable, some have a different way of handling saved games. (read: incompatible) Being forced to use the latest version is not good.
I don't believe Impulse has any DRM. You can set it up as an external game in Steam and get all the benefits of the Steam overlay. Save yourself $10 and some annoyance at the same time.
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drug test kit