Try the dollar store for favors and stuff. Something my son’s friends love to get (I have yet to understand why) is sticky note pads (the 3″ x 3″ size). You can get packs of mechanical pencils from your 99?
store. Add some candy and a cheap game (like a maze) and you are good to go.
For something fun, what about a treasure hunt around your house (including the couple on either side of it – on the outside only) with clues along the way. You could also make a cake that looks like a treasure chest. There are moon walks that are cheaper then $100.
So I you wanted to do that you still could. I believe one place close to me (in Houston) was around $50, but you did have to get it set it up & bring it back (and reserve it about a month in advance). I did that a couple of years for my son, Then had a picnic table set up so they could play Pokemon or Yugioh games for some downtime.