This is a fairly expensive motherboard.
It's $399.95 here:
http://www.notebookparts.com/products/description.php?II=23849... $399.00 here:
http://www.lapzone.com/servlet/the-21589/HBL51LA-dsh-3081P-dsh-3690--Acer-Aspire/DetailThe best option seems to be an exchange. These folks will exchange the motherboard for $249.95 (or sell you one outright for $379.95):
http://www.notebooksolutions.ca/zc/index.php?main_page=product_info&products_id=2648Note, however, that there were several (non-interchangeable) variations of the motherboard; so be sure you correspond with them and provide your exact part number so you know you're getting the right board.
If your friend's "gutsy" ... and willing to risk $50 or so, you might want to see if you can get this for a lowball bid ($20 + $15 shipping is the best possible price) -- and then exchange the motherboard. As long as the problems with this system aren't motherboard-related, that would be the least expensive way to get another motherboard.
http://cgi.ebay.com/Acer-Aspire-3690-BL50-Laptop-Windows-XP-70-GB_W0QQitemZ120399972675QQcmdZViewItemQQptZLaptops_Nov05?hash=item120399972675&_trksid=p3286.c0.m14&_trkparms=72%3A1234%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318%7C301%3A0%7C293%3A2%7C294%3A50 [No guarantee, however, that you could get this that cheap; or that it will even work !!]
Another alternative is to try one of the laptop/motherboard repair services that advertise on e-bay. These also entail some risk, of course. Here's an example:
http://cgi.ebay.com/LAPTOP-MOTHERBOARD-REPAIR-ACER-ASPIRE-3690-461405BOL20_W0QQitemZ140302834411QQcmdZViewItem