Disclaimer: I have no idea where to ask this question. http://ux.stackexchange.com/ seems to be the best fit.
Imagine we have an ad running on Facebook. Is it a good idea to include the price for the product the ad is marketing in the ad (e.g. get this for $300) or is the idea to just lure them with the ad and get them to click through to the site (where the price will then be stated)?