Oh, I just discovered that you can install the Kindle app on a PC! So I guess I don't need a tablet or an e-reader after all, although it would be pretty nice to be able to read wherever I wanted, rather than having to sit in front of my computer... Hmm, I'll have to think about this some more.

Edit: Well, it doesn't look like you can read the Kindle editions of manga through the PC app for some reason. That sucks. I guess it's back to looking at tablets.