If you've settled on the company to do the work, that figure is very much in the ballpark for the cost of an upgrade from plaster to a "standard grade" mini pebble. However, the pool remodel market in So Cal is very robust, such that bid shopping can get you a surprisingly wide range of pricing. Here in San Diego, I secured a bid for mini pebble that matched bids for a plaster finish - and could not be happier with the results (moreover, his lower bid included a complete "chip out" of the old plaster vs. roughing up of the existing plaster and then applying a bond coat as prep for the finial finish).
Also know that mini pebble itself has a wide range of pricing, depending on the mini pebble line you go with (and varies even within the same mini pebble manufacturer).
The key is to get as many bids as possible from PBs that have favorable review posts on Yelp.