Repairs Needed on three Laptops

We are a non profit having fits with our macbook laptops. We are unsalaried volunteers working with trafficking victims and money is not our strong suit! Anyway I thought I'd establish contact and see if there is anything you can do for us. By the way our web set is www.faceofjustice.org We are in Costa Rica but I have teams come each month to do Community Service projects. So if you can help, one friend would mail them to you and then you'd return them to a different friend approaching their date to come here.

#1 was diagnosed by Apple to need a Retina Display (15" Macbook Pro) and logic board

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#2 was diagnosed to ned a logic board AND retina screen (also mid-2012 15") so I have found some services on Ebay that say they are 99% successful fixing logic board issues.

#3 is a 13" Air that turns on but the keyboard and trackpad don't function

Question, if I send you the logic board from #2 and the other two units, can you offer me some kind of general pricing...knowing their are many unknowns and potential cost or parts? We are fine with used parts by the way, and almost prefer it to keep costs down. Thanks. Steve Gilroy Face of Justice Ministries