Hello, I'm just beginning with photography so please bear with me!

I have a Sony A290 digital camera (http://www.comet.co.uk/p/Digital-SLR...s-Bodie/656917)

.. and I'm really interested in experimenting with a bit of wildlife photography. However, I've been tracking the web for telephoto lenses and there are so many that its left me a bit bamboozled! I'm a student and this is just a hobby so I don't want to spend excessive amounts of money, but at the same time I want a lens good enough to take decent photos.

Does anyone have any suggestions on a reasonable lens to buy for wildlife photography?
Or any suggestions of what I should be looking for?


I found these two that seem too good to be true:

http://www.overstock.com/Electronics...3/product.html

http://www.overstock.com/Electronics...6/product.html

What do you think? Do you think I need a lower aperture for decent pics? And am I overlooking an extreme negative of these lenses?

Thank you for your help!