If I'm not bothered about acquiring and reading books on it (per se*) but am more concerned with wanting to upload PDFs and word documents, to the extent that I don't need a wireless connection or anything (so essentially, a glorified USB stick with a screen), is there a better/cheaper option than the kindles and 'proper' e-readers? Or is everyone 'kindle or GTFO'?

* Mostly for work reports, study materials, etc I can see it being massively useful, but happy to continue reading novels in paper form so don't want to pay for that feature if avoidable.