I usually buy the bulk sacks from my LHBS, but sometimes when I know I won't be able to get to the store anytime soon I'll buy from Northern Brewer. There are also group buys for pallets of grain periodically on the HBT website. I've never participated, but the pricing is very attractive.
For hops, I've gone to HopsDirect/Puterbaugh Farms, and FresHops for most of my bulk purchases. LHBS for small purchases. All this may change now that my LHBS is pretty damn big, carries more bulk stuff, and has a web presence. I also grew my own hops at my old house, so a few of my late summer hoppy beers had "free" Cascades and Centennials in them (only the late additions since I didn't want to guesstimate the IBUs). Whenever we finish building and landscaping around our new place, I'll get some rhizomes and start growing again.
My BeerSmith software tracks all my brew prices but I don't have access to it at the moment (on another computer) and I'd have to double check that I entered real dollar figures when I put the items in inventory. Cost went WAY down when I went all-grain and bought in bulk... going from memory, base malts come out to $1-1.50 per gallon brewed or something like that. You still have to factor in specialty malts and hops, plus depreciation on equipment, non-recipe consumables (water treatments, cleaners, sanitizers), energy cost, etc. but suffice it to say if you are going to brew your own, you can beat commercial prices even brewing extract brews, and with all-grain it's a no-brainer.