I got a costco membership last year for the same reasons you are planning to aswell, and in some cases, its overall cheaper. One example is milk where two gallons went for 5.99 while if I bought the same two gallons, it would come to 8.00. Costco is usually good with roomates, but the biggest problem is if those roomates have certain tastes and preferences.
With all the things you listed, the membership would be worth it for those items, but since they come in bulk you would be going there once in awhile unless your also going there for necessities(Milk, Eggs, Bread, Meats). Its also a great place for booze(lol) too if your 21. In California we also have Smart and Final, which is kinda like Costco but does not need a membership. Do they have something like that in Texas?