I haven't been there in about 2 years, but Cabo can be pretty pricey so I really don't have a lot of budget ideas. As far as beer goes, almost any corner store in town would sell you a cold one (in a small brown paper bag) for one dollar US, (don't know the exchange rate right now). Snack food wise, there are lot's of small stalls/stands that sell tacos ect..... all around town very reasonable. Just look for the stands where the locals and cabbies hang out. If you like seafood and sushi, you should try Nick San's, I really enjoyed it when I was there (again, that was a few years ago).
Hope you have a great time and please report when you get back.
"You wouldn't know a diamond if you held it in your hand. The things you think are precious I can't understand" STEELY DAN.