We don't have a music limit, per se, but we like to keep it under $20 or $30 as we no longer purchase Prime Cut's, RPM or Promo Only. We have accounts at 1/2 a dozen legitimate pay to download sites and get the music we need there.
If it is a song that will most likely get played once, we will still go ahead and purchase it but we will limit these "one play" songs to only a few. We find that in nearly every case, the client will have these songs so they offer to bring them to play. (B&G that just left the office asked if they could bring some CD's. Of course we said yes!)
We too offer free earplugs but have never given any out at a wedding but have given out several (to older guests) at revivals and school dances.
We may also hand out free glow stuff if they are "old" and have had them in the truck awhile.