I gave you some suggestions on the other post, but I also like the idea of a pinata that is shared by all. You could use candy but also small non-edible prizes. You could also turn the "goody bags" into prizes for games - we always had treasure hunts, sometimes random and sometimes with written clues. With a lot of kids, you can do teams. Then they split up what they find, and everyone shares. There's no real goody bag after that - just give them an empty bag to put their stuff in.
I also think it's important to give the parties we can afford. Guests shouldn't come to a party and expect $10 in goodies to take home (and I know some do), and people shouldn't invite 20 if they can only afford 10 kids. (I know, you hope that of the 20 kids invited, only 10 will come! But it's so hard to predict!)
I also know that it's hard to disappoint a child because the parent didn't RSVP, so you may not want to deprive the kid of a goody bag. However, if you do so, that parent will never fail to RSVP again. It's also okay to open the door with a real look of shock on your face when someone arrives whom you did not expect - that's harder if you don't know the kids or their parents, I realize - but there's nothing that has a greater impact than a blank look of surprise and a hesitant "Oh, um, I had no idea you were coming..." Then invite the kid in and say "Come on, we'll squeeze you in and find a cupcake for you!" Give the kid a big smile but take a minute to do that! It's okay to say to the parent, "I really would have appreciated hearing back from you."