If I want to buy the defect electrical stuff from Costco to repair and
sell it back at Washington State, How and where I need to contact.

Hi,
After checking with Google and other search engines, I found that it's
better to contact Costco stores to get the exact details about the
electrical defective items.

Check out this page to find the nearest place for you in Washington
for Costco stores. It will give you a list of all the places in
Washington where its stores are located and you can  select the places
near to you. It gives the address, timings and features of that
particular store.
http://www.costco.com/frameset.asp?trg=info%2Fcostconews%2Flocations%2Flocations%2Easp&log=


Also check out this page of Costco,
[http://www.costco.com/frameset.asp?trg=info%2Fcostconews%2Fcontacts%2Easp&log=]
Here they have given the contact details for wholesale purchase,
vendor inquiries.

Search items used:
Costco
://www.google.com/search?hl=en&q=Costco

Costco +Defective+items
://www.google.com/search?hl=en&q=Costco+%2BDefective%2Bitems&btnG=Google+Search

I hope you'll be able to find the correct item from them.

Regards,
netcrazy-ga