I can't recommend it for your one and only tablet, but here's the opposite of expensive:
Pandigital » Pandigital Novel eReaders
I wanted a screen small than my 10" netbook and larger than my I-phone. Mainly to be used as an E-reader, but wanna check email and the news on occasion. I paid $77 re-reburished.
Drawbacks are only: Touch screen needs more pressure than an Apple Product and you have to "root it" to take Android Apps...works good for what I want it for.