Makerbot Replicator 2/2X Ramps Conversion + Heated Bed + E3D

Hi, a friend have gathered a used Replicator 2, with lot of things to fix, so I have decided to convert it to Ramps 1.4 + Arduino to a basic question of cost, because MB spare parts are too expensive for my budget, and I also prefer Open Source systems.
Last but not least I was wondering to maximize the print area and add a heated bed to prevent PET like materials from warping.

Then I found this very good topic right here (See "Remixed from") it has been a good starting point for me, thanks