Pulled Pork BBQ sauce

20 oz of sauce is enough

Wow, 5 butts for 25-30 people?  That's like 35-40 lbs of uncooked meat, unless the butts are cut down in size to 4-5 lbs each.  I would do two 7-8 lb butts for that many people at work who raved about the meat, and still have leftovers. 

If you pick up some cheap ($1) 12-16 oz plastic squeeze bottles from the grocer your sauce will go a lot further.  I found that people use less when it is in a squeeze bottle.  You could have two bottles of each type and probably bring most of that home. 

Don't forget a finishing sauce, like Chef JJ's.  It is a seasoned vinegar that REALLY complements smoked pork.  A couple of squeeze bottles of those are REAL easy to put together.  Just use the Forum's search feature for "finishing sauce" and several recipes will come up.

Have fun at the party! 

PS.  My wife came home while I was writing the above and several folks helped you.  Looks like you are on track.