i'm not sure if this has already been cleared up, but in an earlier post some people were asking about housing in SD. i went to ucsd as an undergrad and still live here.
i think eraserhead was talking about downtown san diego apartments. someone was replying as if he meant downtown la jolla- two very different areas. downtown la jolla's studios will run you much much more than $700/month for a studio, and you don't want to live there anyway because traffic can get horrendous.
downtown san diego, on the other hand, is pretty far from UCSD but much cheaper. the longest it's taken me to get from la jolla to downtown SD was 1 1/2 hours at 5 pm. not sure about the morning. i don't think the traffic is usually that bad, though.
other areas: as aforementioned, la jolla itself is pretty expensive, but very nice apartments. if you can handle a few roommates, it's not a bad deal. there are SEVERAL apartment complexes about 5 mins from campus. my first year off-campus i had the master bedroom for $500/month, two roommates.
the next year i lived in mira mesa. cheaper (and low quality) but inconvenient as hell, since there is no good way to get there by the freeway. just a long, traffic-congested road.
this year i live in del mar, which is a beautiful town by the beach. quite expensive, and the only way i can afford it is to share a room.
clairemont mesa/university city usually has affordable apartments and is pretty close to school as well. the only problem with clairemont is the quality of the apartments...
hillcrest is a really cool area with lots of stuff to do. it is just north of downtown san diego. i'm pretty sure the area is expensive, though.
those are all the areas that are close enough to la jolla to live. east county, anything north of solana beach/del mar, and places over by san diego state are too far.
on a side note, i love san diego. ucsd is a great school and i would encourage anyone to go there if given a choice (especially over UCI).