Respond_with and ajax

Rails
1

Suppose I have this controller:

class SalesController < ApplicationController
respond_to ???

def get_price
@price = Product.find(params[:product_id]).price
respond_with ???
end

end

  1. What do I specify for respond_to() so that get_price() will accept
    ajax requests?

  2. What do I specify for respond_with() if all I want to do is return
    @price?