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I've never even heard of something like this xD
Pretty awesome tbh.
However, I did find a few on Ebay for cheaper.
Maybe you could check out these brands too, and possibly find some reviews about them?
Hope this can help you out
#1 Adesso Cyberpad $79 and $77
#2
Medion Digital Notepad - $86
#3
Genius G Note 7100 Portable Digital Notepad - $94