It's 5$ for a roll of ACR100 in 120 and 57$ for 20 sheets of 4x5. Doesn't seem particularly expensive to me.
Also 400TX is 4.39$ (after rebate) in 135, and 25$ for a pack of 5 in 120. 50 sheets of TMY2 is 96$, etc. Also not particularly expensive (although I wish the 4x5 were of course cheaper).