I own a QuickPad Pro that I bought off of ebay for $50 or so. I’ve never really used it that much, although one of the things I like about it is that it is DOS-based, which is appealing to me for obscure reasons. However, the screen angle has always been a bit off for me and the fonts are really hard to look at. The Alphasmart Dana looks like a nice alternative and has garnered some nice reviews for higher ed use. Taking a look at completed searches on ebay, it looks like the AlphaSmart Dana usually sells in the $100 range. New, they cost $350. There is a wireless version that I think would probably be more of a distraction than anything else. It sells for $429. New, both of them include Documents to Go, which I’ve used pretty extensively. It’s a very useful tool to exchange Word documents, etc. with desktop versions.
Here’s a short list of devices that sport full-sized keyboards and enable you to take notes, while also permitting you to do some basic hilighting, editing, deleting, etc.