BeerBorg

I bought a lot of lme on Amazon. It was cheaper than my lhbs, which surprised me.
It was 3.75/lb. My lhbs used to sell it for $3/lb if you brought your own containers.

I think yeast is about $3-4 a packet (i have a lot and got a deal, but that doesn't count). I buy hops in bulk (and grow my own). So figure 50c/oz.

All grain is cheaper, but I'm not up to all grain. I'm not sure I'm up to extract with a boil, actually.
When i look at the cost of an extract batch with a hop boil vs a mr beer refill, the difference seems minimal.

Is my math off, or is mr beer a better deal than i remembered?

Mr Beer kits.... I have nothing good to say about them. As far as kits being cheaper? In a lot of cases now adays, can be. I have found a couple recipes close to my own so I bought some and brewed them. The all grain kits close to my recipes are actually less than my cost to put together the grains, hops and yeast and I buy grains by the 50lb sacks. So yes, some kits are better deals. Some, not. Shop and compare. As far as using DME/LME, been a long time since going that route so can't speak of them. Good luck