I usually just lurk, but I want to voice my agreement with what others have said about the value of KSP.
Generally if I play a game for more hours than the number of dollars I spent on it, then I consider it a good buy. Twice as many hours: excellent purchase.
I think I paid $20 for KSP, and as of right now I've played 660 hours. 33x as many hours, or a cost of $0.03 per hour of entertainment.
Also, all those hours show that, for me at least, it's more than a game, it's a hobby. Besides rock collecting, I can't think of a single hobby that I could sustain for years with $20. Even with the current price plus this new DLC: hundreds of hours of fun over years for $65: definitely a good deal for me. I actually really hate the current trend of adding paid DLCs for everything, but if the further development of KSP required a subscription then I'd totally be willing to pay that, so a random $15 drop shouldn't be a problem.
BTW, I'm not necessarily saying that it's a great deal for everyone. I also bought KSP for my wife (she is a gamer, but isn't into simulation stuff), and she played it for maybe two hours. At full price that's already $20 an hour. It'd be silly to say that any KSP DLC was a good deal for her.
I've had tons of fun with KSP and, unlike any other game I've gone through, I can't imagine I'll ever leave it behind for too long, so I'm in full support of chipping in for a little more polish and content.
