This is a great idea ^^ The only issue is you would have to buy the pcb to heat the bed. Probably all together cheaper than XYZ if unless you have a valid warranty. EBay would be another good place to check, I have seen them listed $10-15 cheaper than buying from XYZ.
i use multiple single edge razor blades, make sure the bed and part are cold, or else you will warp the edges/corners, start a razor blade in each corner and gently tap them around the print to loosen it. Usually it will just pop off, if it still doesnt, i take the handle of a screw driver and tap it (with some force) on each side till it pops off. I do this all the time, cause i would rather my completed print be difficult to remove, than it coming loose halfway through a 12 hour print and having a pile of filament laying there.
I used copper tape for stained glass to build my own heater for an oversized print bed on my Robo3D. I figured out how long the copper tape needed to be to match the resistance of the standard heater then spaced the strips so they covered the whole plate. Once installed on the glass they were soldered together and covered with capton tape to prevent damage and shorts. The bed heats quicker than the production bed. Here is a picture of the bed while printing a new customized seatback for my grandsons Big Wheel.