Hi there! I too, am a poor uni student from Australia. I made my choice with getting the kindle and had been loving it ever since. Yes there is the frustration of geographical restrictions when buying from the amazon stores, but it is also probably the biggest selection of ebooks available to us Australians still anyway. You can always still upload your own books onto the kindle. You can get freebooks from Feedbooks directly on to your Kindle if you got the 3g version too! and turn it off at will when you want to.
Lastly, the pdf support has been working pretty well for myself. I thoroughly enjoy the fact that I can darken the words on the pdf with the new kindle software to view the words better. If you have a phone that charges with the micro USB, they can share the same charging station
I don't know if a ebook cover is going to do much for a drop, I have never let it fall more than 5cm. Maybe you'll find some shock resistant one somewhere.
My angst at the moment is that it reboots by itself randomly(but amazon is releasing a firmware update soon and I had been avoiding it crashing by not letting it go below 30% battery charge (btw this had happened to me only 3 days ago for about 4 times and had not yet happened since I've charged it, im inpatient)) Amazon is also non-contactable from Australia by Mobile phone, but if you have a landline their customer service is highly commendable. Otherwise, I find the kindle a truly enjoyable product.
I was skeptical with the kogan when I saw it, but both Kobo and Kogans are alternative to cheap ebook readers. However, I do not think the Iriver is a good choice at all... before I bought the kindle, I was in and out jbhifi and harvey normans to play with the Iriver. I found the price too high do justify what it does. It is not only sluggish and some what irresponsive, but also the main screen was hard to navigate.
edit *My 2nd choice over kindle would probably be the new Sony range. But I like the key board thing on the kindle that most people probably hate ._." and do not like touch screens on a eink screen device.