cheep 3D printer for around £100

do you have optional part list for 3d printer?

no not really i dont think i can do much with only £100 in the ways of optionals
I just need a bare bones 3d printer that will have relatively good quality output

Good luck. I am working on designing my own printer, and that is about what the electronics cost. You will not likely be able to find what you are looking for at that price. The cheapest printer I have seen is the printrbot Jr. It is $399 and is tiny.

By electronics I meen just the control circuitry, this does not include the powersupply or motors.

If you are looking for guides and information you should go to reprap.org.

I have 3 identical scanners that all have stepper motors i can use im going to buy a few drivers £15 for three

Im aiming to make the same style as ben heck made in 2011 for maker fair

I already have an arduino and i can make any parts of the case for nothing with a laser printer so all i really need to buy now is an extruder and rails for the movement of the platform and the extruder and other small bits like bearings and tubes etc.

Okay, if you already have the electronics yu might be able to do it. I think you would find the RepRap forums more helpful as far as design help on this one. I haven't been able to find a printer like Ben's anywhere and that is part of why I am designing my own. You will need 4 stepper drivers(1 for X, 1 for Y, 1 for Z, one for your extruder). I would use an arduino mega because that is what most of the firmwares are designed to run on. http://reprap.org has a very helpful comunity behind it. I would look on their wiki for how the firmware expects your drivers to be connected to your arduino.

solidoodle and printxel are the cheapest 3D printers I've seen prebuilt.  I've heard you will spend a minimum of around $300 building your own unless you have a lot of the parts already.

You can use http://www.instructables.com/id/Easy-to-Build-Desk-Top-3-Axis-CNC-Milling-Machine/ this and just add extruder head

I agree with the other posters, it's very dificult to make anything under $500 US. The cheapest you can buy as a kit is probably PrintrBot.

Yes you can pull steppers out of a lot of things but they are going to have less torque than even the smallest Nema 17 steppers that people typically use.

Time is money. Is the time you spend on something that might not work, worth more than paying $400 - $500 for known working parts?

mcmaster carr carrys rails acme screws and bushings... but they are pricy...