I'm in literally the exact same boat as you op, I'm just about done the semester with CAD (solidworks) but my entire next year is all about our senior design project.
Luckily my school has a bunch of powerful desktops we use ( which is why I didnt build a pc yet)
You can also get away with building a $1000 setup that would handle solidworks pretty well.
As a benchmark, the ones my school uses are these
http://www.dell.com/us/business/p/pr...workstation/pd
the $1400 one. Building it yourself shouldn't be too hard according to my friend who has a watercooled insane gaming setup that he also uses for school.
An i5 processor "pretty good setup" comes out anywhere from 1000-1250
This is my wishlist if anyone wants to chime in ( not to threadjack but me and op are in the same boat pretty much)
https://pcpartpicker.com/list/d6L6qk