Two 50w cartridges should work well with 1.2mm nozzle and probably get you to 0.6mm layers. FYI - I remembered wrong... I'm running a 1mm nozzle at 0.3mm layer max ..with a 40w single cartridge .. that allows printing most large parts with a single perimeter wall, thus reducing material usage.
You could try saving money by guiding on cheap Aluminum extrusions .. if it is straight and/or you can machine the working surfaces straight, if you have access to a milling machine at school or elsewhere (I have mill and lathe .. a must have when ya get older and want lots of toys, LOL).
If you can find descent E3D clone hot ends they work pretty good and are really low cost .. worst case ya swap the nozzles for high quality real E3D nozzles (this is what I do, since I have 6 printers and spares ... but use the hardened coated E3D nozzles on all, since they last forever and the tips don't wear away like brass ones).
I understand what you are saying ... human nature is to ridicule and troll people in forums, .. instead of constructively helping each other. I understand being your age and wanting to save money
If you go the pellet extruder route ... IMO, the challenge there is how to hopper 1-2kg of material, without that heavy weight having to move with the extruder. You might consider a machine design with a stationary extruder, and a heated bed that moves in X, Y , and Z.