I have some experience with building 3D printers, so perhaps I can give you some useful information.
Regarding electronics, the printer will need at least one extruder, a mean board + arduino 2560, LCD screen, stepper drivers and motors to move the axis. Since you want to build a large scale printer, I strongly recommend using 4 nema 23 motors for the Z-axis, 2 for the Y-axis and 1 for the X-axis. A heated is optional if you only print in pla, but I strongly recommend it.
I ordered most parts of the extruder so far (except for screws and springs etc) and it cost me about $50. An Ultimaker main board + arduino mega 2560 clone are together about $22. I am not entirely sure about the costs for a LCD screen, but I think you can get one for $25 or less. The 2 small stepper drivers are about $5 together and the 2 big stepper drivers are $24 together. The 7 nema 23 motors are quit expensive; $25 each ($175 total). A 1200*1200mm heated bed is about $250, but you could skip this. Without a heated bed, this comes to about $300 (if ordered from china).
There are some more smal and basic electronic components you will need like lots of wiring (I assume your school already has this), end stops, and some more small and affordable components. The costs for these smaller things shouldn't be that high. Also adding fans to the motors would be a good idea (you can get them for about 1$ each from china).
You will also have to build a frame with moving axis. If you can pick all the aluminum parts somewhere up and recycle it, you will be able to cut a lot of costs. Other components you will need besides the aluminum framing are a massive plate or mirror for the bed, lots of screws, belts for the motors, bearings, massive screws for moving the Z-axis, etc. The frame with moving axis could be very expensive, but could be quit affordable too (depending on the parts you can already find around yourself).
Of course you will also need a power supply.
There is no doubt there are components I forgot to mention, but these are likely basic components you can get anywhere and for a reasonable price.
Also, I really hope you or your school already has a 3D printer. You will definitely need some custom components for a built like this. If you have to order these custom parts, it will be extremely expensive! So just print these custom parts with your own printer!
I hope this information gives you some more perspective. If not, could you tell us how big your budget is? Perhaps we can tell you wether it is big enough or not.