It's tough to find issue with the Costco Hot Dog. For $1.50, you get your choice of a hot dog or a polish sausage as well as a fountain drink. I generally tend to go with one of each (even though I really can't tell the difference between the two).
For $3 I get two good size hot dogs and two drinks. You can donate your extra cup to someone else in line who is only going for a slice of pizza, so it makes you feel good about giving to others as well. As for toppings, I apply a line of deli mustard and then load the hot dog up with diced onions from the onion crank (I LOVE the Costco onion crank. I wish they sold THAT in the store). You need to make sure you put the mustard on first, as it acts as the glue to keep the onions from falling off.
A little known secret is that you can also ask for a cup of sauerkraut when you order your hot dog -- and it's free. Seriously! It's $1.50! How can you go wrong?