Malcolm013,

It's not a question of being snotty or greedy. Family/friends or not, I run from projects such as this when the discussion centers around an AVR. It's like trying to make do with a fold down rear seat when one should be using a van.

The potential of needing to convert the mic from balanced to unbalanced is the least of your worries.

Since these are friends, you could give a quick back of the napkin estimate for doing things right -- citing the advantages of a truly commercial installation. If they go for it, do it right. If not, let the kid down the block or the drywall installer set them up. They'll be happy about all the money that they saved and may not care or notice how they are struggling with "minor issues" -- and their guy can take the heat for the "minor issues".