Attached is a link to the Marvistavet.com web site with very good information on Flea Product Comparison and amount of time it takes for the products to work. Really good stuff!
This may change in the future, but right now we have found Frontline Plus available at the least expensive price at Sam’s Club and then at Costco. We have found the price to be the same no matter what size you buy.
Here is the link: http://marvistavet.com/html/body_flea_product_comparison.html