-- Relevant to topic \/
If your birthday was after Nov. 19, I'd say have a WII~II party, but since it isn't.. Hmm... I'd say try to come to a basic point on what everyone would like in regards to events, then go with it. Don't get too detailed (obviously won't be able to, due to limited funds), but keep things interesting.
As for food, I'd say (again) see what everyone enjoys.. or you could be variant and maybe get a lot of little pieces of different types of foods, not all junk food. Even when I go to outings, I don't just try to eat my share of burnt marshmellows but also a bit of solid food (i.e. chili, stew, anything that has some sort of real nutritional value to it).
For my 18th, I ended up being out of town.. and so far, every year since, I've not had the b-day song performed for me (thankfully). Of course, even though I was out of town, I was with my family, and we ended up going out to eat that evening. They forgot it was my birthday (hurray!) until after dinner, so no singing at the restaurant for me.. but I got a free meal out of it!.