It really depends on if you're buying from Mark or the secondary market. There was a double page splash that just sold for $6,000 on splash page. To be honest, anything with a decent zombie on it is probably going to set you back at least $1,000, if not more depending on detail, who else is on the page, page significance, size of the OA, if it was pre-100, pre 48, post 114 w/ Stephen, etc.
If you're buying secondary market, it may be even higher. For a book with 100+ issues and zombies everywhere, there aren't really as many crazy zombie pages as you would think. Which is probably why it's been so good.
Thanks as complicated as that
It would be secondary market pre-100
How about this... Walking Dead #73 page 16 - Half Splash with 2 Zombies, Abraham (2 panels), Bruce, Holly and Tobin (2 panels). The book is the first appearance of Holly, a minor character still around (3rd page appearance)