Errrm...
Non-warrenty repair is $50 for an MM, $75 for an MMM last time I checked, so if someone did do the trade with you... :-
Give away 2x MMMs = $300 loss. Spend ~$250 on repairing dead MMMs and MM ( 2 of each esc say, you didnt specify what you actually have ), total loss $550. Then gain x2 MMMs and x2 MMs, worth total of ($90 x2 + $150 x2) $480. Total loss to that person is ~$70. I know thats only a worked example based on swapping 2 of each MMM & MM, but anyone would have to be mad to go for that deal
I think you'd be better off sending them in for repair yourself dude
