All grain is most certainly cheaper.
Just made a 5 Gal 6% Hefe for $29 -- including hops and yeast. 5 Gal, 4.7% brown for $25, again with yeast and hops.
I've also done half batches and reused yeast with spare hops for $8. What does extract cost, like $4.00 / lb? Grains are about $1.25/lb for base. Surely you need to use more grains than extract, by mass, to reach the same gravity but the relation is around 40% -- certainly not enough to overcome the 220% price difference.
Someone mentioned $40 batches. That's steep. I second the Brewmaster's Warehouse idea, Ed is the friggen man and you get 10% off for using their recipe builder -- just put your grains in and buy it.
Of course my LHBS overcharges for grains (actually, for yeast and hops as well), if I were going there then it would be expensive. Even so, I did a 5% Schwarzbier with their stuff (just shy of $2/lb for German Pils... bit ridiculous), and it still came out to $35 with hops & yeast.