It has been a long time since I have seen a copy of WC3 in the 8MM-style box, but here is one on eBay.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=62053&item=8178957706&rd=1
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=62053&item=8178957706&rd=1