How about the Market restaurant at the Loews hotel near there? Also, Sheerwaters on the back of the Hotel Del does a buffet breakfast for about $25.00, but I'm not sure if they do it on the same days as the Sunday brunch. $70. is pretty ridiculous for brunch.
If you're willing to venture to La Jolla, I love the setting at La Valencia, and the food is decent. It's around $40. I believe.