Just to clarify....
When making bulk purchases from China, you have to accept that there WILL be a certain percentage of DOA components in what you receive. From the Chinese perspective, you are paying very little for the purchase, so you should expect this as a normal cost of doing business in this way.
Should you have an unacceptable level of DOA components, you will find yourself in one of three situations:
1.) Tough s#it. You are on your own. Better luck next time.
2.) You get to pay for shipping of the DOA units back to China for evaluation and warranty (if one even exists) replacement. Shipping FROM China is dirt-cheap. Shipping TO China, on the other hand, often exceeds the cost of your total original purchase--including what you paid for shipping from China to you.
3.) Some organizations will state that they will replace DOA items--at no cost to you--upon receipt of PROOF of the defect causing the DOA condition...often stated as "photograph of the defect". Think of how you can render photographic PROOF of RAM or μP failure that will be sufficiently convincing to an organization that is motivated to discount such proof. In all honesty, it just can't be done.
My experience has shown me that, in extreme cases, you may get anywhere from a 50% to 10% good unit yield from such purchases; leaving you to ask yourself if the calculated price per good unit is an equitable return on your investment of time and money.
Your odds of getting "enough" good units for your needs obviously increase as you increase the unit quantity of your order; but, do you really want to buy 3- or 4-hundred of something to get just 1- or 2-hundred good units to work with?
And that's before you even consider the actual performance specs of the "good" units you receive.
If you want to get your hands on functioning used components, have you considered contacting the various e-waste recyclers in your area?
Many do offer "system-pulled" components for quite a good price.
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