The site I used doesn't list a Subaru part number, but go here: http://www.subaruonlineparts.com/oempartscat.html
and search Subaru, 2010, Legacy, console, front console, cup holder. You'll have a choice of manual or auto trans, although I'm guessing the cup holders are the same. It's $33.34 plus shipping.
I should have checked the molded part number on the cupholder before I installed it.
Anyone know of a site that does "reverse" part number look-ups?