I've never had the K1, but I've read reviews of many people liking it. I'm sure you could get that version at a discounted price, especially since the K2 is somewhat old news with the new one out there.
Unless you need to use a lot of PDFs on it or need it for business reasons, I would be against buying the newest one, the DX (I think that's what it's called). It's just so much more expensive, and a lot bigger than the K2/K1. Unless, you're looking for that ... for me, I like something smaller so I can stick it in my purse and go.
I absolutely adore the K2. Although I haven't gotten any subscriptions yet, I like that they all arrive early in the morning wirelessly to the Kindle and that the magazines arrive to your Kindle before they hit the stands. So very nice. It's also good for those who read excessively and/or travel a lot. Books delivered wirelessly are almost always cheaper, and there are many under $10.
It was definitely an expensive purchase, though. I looked over every single review I could find for every e-reader I could locate. I thought about it for quite a while before I decided it would be worth the hundreds of dollars for me. I just really like the way Amazon does their e-reader. I haven't regretted the purchase ... even if I've missed the money.
To note: If you get the K2, it doesn't come with a case or cover. Because the Kindle is so fragile (I've read reviews of it being dropped one foot in the house and it never working again) many have opted to get one. Cases range anywhere from $20 to $150, maybe even more. I haven't bought one yet (still looking to see which I like the best). It's definitely something to consider. (And another way to take money out of our pockets.
)