El Burrito Junior (multiple locations, many along PCH). Cheap is all relative. I think they charge $85 for 60 tacos (beef or chicken) or $50 for 30. I enjoy their shredded beef. I haven't had the chicken tacos.
They have 2 Torrance Locations:
3830 Pacific Coast Hwy, Torrance - (310) 373-5405.
21141 Hawthorne Blvd, Torrance - (310) 944-9200
I think you'd have to pick up the tacos and bring them yourself. They have very good salsa, which I'm sure they'll give you... and some nontraditional chips (they basically give you fried, crunchy whole corn tortilla rounds that you break up yourself).
I enjoy this very small, local chain and it's a go-to place for quick tacos and burritos when I don't want to do sit down, tableside service (although they offer it at most of their locations... at least they offer tables to sit on).
El Burrito Junior
21141 Hawthorne Blvd, Torrance, CA 90503
Two of the most auténtico taco places in the area are Los Paisas and El Taco Loco. Both are located on the outskirts of Torrance (Harbor Gateway area), but their addresses indicate that they are Torrance businesses.
Whether or not they cater, that's for you to determine ;-)
21168 S Western Ave, Torrance, CA 90501
El Taco Loco 7
22502 S Western Ave, Torrance, CA 90501