prints get very stuck to bed, very difficult to remove

[curious aardvark]

a sheet of PEI is cheaper than buildtak and much better.

Build tack works, but getting stuff off it can be tricky - never use it with polycarbonate - for example :-)

Personally I use printbite. Which may or may not be a form of PEI - depends who you ask. Jason (the seller) says it isn't, other people claim it is.
All i can say is that stuff sticks to it when it's hot and comes totally unstuck when it cools down.
PEI - a 200x200 sheet of which can be had off ebay for under v$10 - is supposed to work in a similiar way.

Also magigoo - a special glue/coating - claims it also works in the same way. And that can be easily applied directly to your glass plate.
I haven't tried magigoo yet, but have tried dimafix - which works well, but does like to hang on to stuff.
Magigoo claims it release when cold - so probably some solution of a pei type material. They're clever buggers these chemical engineers :-)

My work horse printers have had sheets of printbite for about 5 years (same sheet it doesn't wear out). And it does take an awful lot of the hassle out of printing.
It's not magic you still have to get tyhe print settings right, but it's as close to magic as I've yet found.
Given the cost, I'd be inclined to try the cheap PEI or magigoo first. I have a sheet of pei, just haven't got round to testing it yet.
When I've finished modding my ctc i3 pro b - I'll be doing tests on that.
Next job is to bolt the thing to a sheet of 5mm aluminium. The biggest flaw with it is that the base is not securely fixed to the gantry, move the printer and it goes out of calibration. Once I've got it bolted to a rigid sheet of aluminium - it won't do that anymore, and once calibrated with the locknuts I added - should stay calibrated almost indefinitely :-)

That currently has a sheet of some stuff (could be buildtak) I got from lankeda.com at the tct show.

Also when i find the big envelope the pei came in - currently unsure of it's whereabouts ;-)

There are a lot of options out there, most fairly inexpensive - so try a few and keep what works for you :-)