You mignt want to check out Innoversal Papyrus (8"), will be released in October, at around $300.
http://www.innoversal.com.tw/en-us/p...s/papyrus.aspx.
However, I find reading academic articles (two or more columns) even on 9.7 screen rather difficult. They usually don't reflow very well and I often get some strange symbols.
Pocketbook 902 will be around $300, I think. But Innoversal will enable you to annotate, and PB902 won't.