iFixit links and parts prices are up, in case this hasn't been posted:
https://www.ifixit.com/collaborations/kobo
Looks like a battery will run around $45 for the Libra Colour, a screen replacement, $130. Still a good argument for using a case, as breaking a substrate is not going to be a cheap fix.
Other parts include motherboard, front and back covers, and these are modestly priced.
I'm still resisting. I just don't see a smaller color device beating my Sage in any way, considering the majority of my content doesn't have much color besides covers. But I have to admit, I'm also very curious and enjoying all the excitement!