Discount code savings frequently are based on discounts off of the full price rental rate, but even with the savings are often more than the sale rental prices. I agree with the earlier poster that the upgrade codes are a good deal, since you can book a class smaller than you want/need at the sale price for that size vs. the one you'll get. Some offers also are for free days and things like that, so those typically will result in savings off of sale rates too.