Ubuntu / Android dualboot capable tablet

For ages I've been seeking a cheap tablet that is able to run ubuntu natively. For many reasons:

• Opensource drivers means you will always be able to install newer ubuntu, android and linux versions. GPU, video, audio...

• Desktop, I love a multitask desktop (Lxde, Xfce Unity, gnome, kde... so many choices) and to arrange windows the way I want, not one big app covering the whole screen.

• Because it's possible

Wich one would you advice? In terms of hardware, what should I look for that has opensource drivers? 8" IPS screen with hdmi, usb-otg, and bluetooth please

The price of Nexus 7 is much more expensive outside USA (200 €, 200 UK pounds...) and also it lacks microsd slot and a bigger screen

So far I found this:

porting Ubuntu Linux to RK3066 devices http://www.slatedroid.com/topic/41513-ubuntu-linux-1210-on-the-pipo-s1/ I assume it would be possible to port it to other RK3066 devices like: Pipo s2 (problem: not IPS screen) Momo8 (problem: weak wifi on android 4.1) ...

http://hardware.slashdot.org/story/12/12/02/1347200/pengpod-hits-funding-goal-plans-to-ship-linux-tablet-in-january

Hardware for XBMC http://forum.xbmc.org/forumdisplay.php?fid=112