Actors are too much to afford, non-actors can't act

I want to use recorded conversations for my project but, unfortunately, ever person I've considered cannot act (I should have taken theatre). Maybe I can use natural sounds -- or Stephen Hawkings voice synthesizer -- to make my clips. I was looking forward to script dialog and record natural conversations but, for the subjects(people) I have chosen, they sound like they're trying to act in both situations -- I know we're suppose to blur the boundaries but it sounds horrible. Maybe I shouldn't use my friends (they're both computer nerds) but I don't want to ask strangers to perform for me -- it's weird and creepy. I think I'll have to work with them, hoan their skills. Maybe I can use recordings of other people talking and mash it up. I guess that's a good idea... maybe.