I recommend you stay away from cheap tablets. They tend to get really bad reviews.
As desertgrandma pointed out, lasting through college would be quite a lifespan for dedicated ebook readers today. Amazon is coming up on the third anniversary of the original Kindle this year and they've just released the third generation of the device. Technology changes fast and by the time you hit college, you're probably going to want something better or more up-to-date. If the idea of this turns you off, you might be better off waiting for college (ask for one as graduation present
). You seem to suggest that textbooks were not a consideration, which is to be expected from a high school student. High schools give you whatever books they give you, and that's the end of that, pretty much. However, in college you're going to be looking for all sorts of ways to cut down costs on textbooks. Unfortunately for me, the books I've needed haven't been available for the Kindle. A friend of mine, on the other hand, said this semester he was able to find most of his books on the Kindle. Amazon is really putting an effort into getting more textbooks onto the Kindle. In my opinion, current eink screens make for a poor textbook experience. They're kind of a pain in the ass to work with when you're studying and you need to flip back and forth quickly between pages. The search function is nice, but it can be slower than tabbed pages. Images also tend to be low quality and graph support isn't that great. These limitations generally apply to more technical books. The Kindle (or any ebook reader) is great for linear reading--i.e. any book you're going to read beginning to end without jumping back and forth between references and such.
Something better is going to come along by the time you graduate high school. The tablet market is still new and color eink screens and mirasol screens are rumored to be just on the horizon. When I was in high school, I often relied on my computer for reading ebooks because I didn't have the money to go buy all the books I wanted to read. I would have LOVED to have something like the Kindle in high school. But you really need to weigh the costs and benefits. If you think that you could afford an ebook reader today and another one a couple years from now (or if you think you could finagle one out of your parents, more power to you, haha), then by all means, go for it. They are great for reading fiction and you'll probably find yourself reading more than you did before. Otherwise, I recommend you just wait for college. By that time an ebook reader will be more useful for you and you will have a more capable device.
When it comes to the actual Nook vs Kindle debate, I'm very biased. I've owned every generation of the 6" Kindle after I made the switch from the Sony PRS-500. I think Amazon has really made the best device and I think they definitely have the best ebook store. Their customer service is also superb. That being said, I love Barnes & Noble as a book store. I go there all the time. Almost every time I'm there, I play with the Nook. They've made a lot of great improvements since it first came out. It's much less buggy and it's more responsive. For me, however, it still doesn't measure up. Highlighting, note taking, and dictionary lookup are all better implemented on the Kindle, in my opinion. Using the touch screen to control what's happening on the eink screen is sometimes difficult because I find myself trying to concentrate on two screens at once. I think tactile controls on the Kindle make for a much better experience. Also, if you do ever decide to use the Kindle for textbooks, you'll probably have more options at Amazon.com than BN.com, though that may change as B&N ramps up their competitive efforts. The Kindle also allows for web browsing over 3G, meaning you'd be able to access sites like fanfiction.net from anywhere. Since I got my Kindle 3, I've been using the browser even more than I did before because the newly introduced article mode makes reading in the the browser a much nicer experience than before.
I hope this helped some with your decision-making process. Good luck!
