Although $100 of old manual glass might be better optically than an autofocus lens of the same price, I don't think it would translate into better pictures in practice. Trying to quickly focus a 35mm lens on a focus screen designed for slow autofocus lenses will be very difficult and probably give quite a few slightly out of focus pictures whereas a Canon EF lens will quickly focus accurately.
The Canon EF 35mm f/2 is a good choice but won't fit in your budget although consider that if you buy it used for a good price, you could sell it at the end of your course for about the same as what you paid for it, making it essentially free. It is a lens still in demand as it fully works with all EOS cameras. There are also some great deals on used EF 28-135mm f/3.5-5.6 IS USM lenses since Canon sold so many in kits recently. Although is also out of your price range, you could resell it later without loss if you paid not more than $250 for it.
If it doesn't have to be exactly 35mm, the new Canon EF 40mm f/2.8 STM would work great and give you a tiny and lightweight very sharp lens with almost no chromatic aberrations or distortion. These are about $200 new and there isn't a used market yet so you would take a bit of a loss selling it after your course.
The Canon EF 28-105mm f/3.5-4.5 USM and USM II lenses can be had for around $150 used and are quite good with very fast focus.
If you really cannot spend more $100 now, there are plenty of used Canon EF kit zooms on the market that would work fine for you and be fairly saleable when you are done with them, or keep them for use with a dSLR. The sharpest choice in the $100 would probably be the EF 28-70mm f/3.5-4.5 II. I'm always surprised how sharp and contrasty this lens is.
Otherwise, the original EF 28-80mm f/3.5-5.6 USM with the metal mount is quite a decent lens with ring USM and are often around $100. Distortion and chromatic aberration are low with that one. The 28-80mm f/3.5-5.6 II USM and III USM are quite sharp although they look and feel very cheap. These would be not more than $80. Avoid the 28-80 IV USM and V USM and the original non-USM and II without USM as those four are quite poor optically. The 28-90 lenses are serviceable but not that sharp. The EF 35-70mm f/3.5-4.5 lenses are under $100 and aren't bad although not nearly as good as the 28-70.
There were quite a few other Canon zoom lenses that cross 35mm available in the sub $100 range. EF 35-80s usually go for under $50. See the Canon Lens Museum
to see all of the Canon EF lenses available. I've used almost all of the low-end Canon lenses. Unless you are scanning your film for editing in Photoshop where corrections are easily made, then it is probably good to choose a lens with low distortion and chromatic aberration.