I have a few in mine, but I agree with others regarding the bulk. I also highly recommend stripping them down as IronRaven suggested. Lots of things you won't need.

I prefer to make my own..check the meat aisle at your local grocery store, you can find several kinds of tuna in foil packs, here locally in OK, they even have precooked hamburger meat in foil packs.

I also highly recommend having a condiment selection. I have one too, but I just acquired mine from local eating places. ketchup, mustard, salt, pepper, parmasean cheese, hot peppers, soy sauce, barbecue sauce...etc. That website is pretty cool, but you shouldn't have to buy this stuff, just use one less ketchup each time you go through McDonalds...it builds up fast.