I'm not sure if this is really the right place for this, moderators feel free to move/etc. I just thought I'd pass on some information that Home Depot is running a promotion for free solid core upgrades on their interior doors. If I remember, the offer was good until 1/9/2013 (but don't quote me on that).
I just ordered a 1 3/4" solid Jeld Wen door through them and it saved me about $60. Not a huge deal in the grand scheme of a dedicated home theater build, but for those trying to work on a tighter budget (such as I'm attempting to do) every little bit does help.