okay, let me be the black sheep of this post. lol.
In your case i could go either way, if you feel firm you and your class can mig weld , i would build a mild steel car on a budget and everything could get done hands on by you and the students. I also do not know to what extent you are wanting to build a car, tube chassis, back half with cage or so forth.
If you are wanting to build a full tube chassis i would do cm and let your friend weld it up, a typical 1.250" tube,360 saddle should not take more than about 30 secs to run a tig weld around, but you have to factor in, getting situated to run the weld, under the car , inside, where you cant reach and on and on. if the fit is tight, factor the weld time is twice what a mig weld would be, but yes every main thing needs to be tig welded. I wouldnt worry about resale that much either unless its a full chassis car. just my 2 cents.