My local butcher does a kilo of ribs, 2 kilos of sausages (incl gorgeous spicey ones), 15 chicken pieces (thigh, drumstick, wings) and 10 burgers (beef or pork and apple) for €25. I've never gone far wrong with that as the base of my BBQ. Chicken skewers are good too. Maybe some steak and some baked potatoes.
I agree with Caveat about not going mad as there's enough to do. I put the chicken in the oven for 50 minutes before giving it a turn on the flames. This gets it out of my way and also makes sure it is well cooked.
Then you just need some potato salad, coleslaw, cous cous and a few sauces. Aldi do lovely sauces incl a great tomato and chilli.
And a big contatiner full of beer!!