Could you not say BYOB? Food can be made pretty cheap as well and as far as decorations, you just need to get creative or buy second hand.
I think this is a great way to view it too. We're at a point where it's tough to get the house ready for a party AND the yard decorations, plus have the expense of buying new props as well as food & drink. We have two little kiddos who are budget drainers - ha ha ha - and when DH & I do have guests, we want to treat them well, so our food & drink budget always seems to grow.When you know how much time and expense you've put into it, it's easy to think of your friends as free loaders. But we like to think we're the glue that holds all our friends and family together. No one else would tackle this kind of party. I love to do it. I love making memories for everyone, especially the kids. I think of it as a gift to those that know us.