$75 and hour charge is reasonable - and pretty consistent with what I've experienced with other companies. In my experience, the minimum service charge is 1 hour which I think it fair. 4 hours minimum to check them out seems really high - especially if nothing is wrong. Did I misunderstand you? In other words, they told you that it will cost at least $300 each, $600 total to check them out. Something is wrong there.
I just sent one of my M200's back to B&K to check out an intermittent fault - it cost me $96 including labor (1 hour which is the minimum), parts - one part bad (a switch) and few other minor parts they replaced to bring them back up to Spec, packaging in a brand new factory box, and shipping cost back to me.
I just sent one of my M200's back to B&K to check out an intermittent fault - it cost me $96 including labor (1 hour which is the minimum), parts - one part bad (a switch) and few other minor parts they replaced to bring them back up to Spec, packaging in a brand new factory box, and shipping cost back to me.