It doesn't really matter which brand you use, they're all basically the same, with copper oxide as the main ingredient. Copper oxide is heavy stuff, so the more they put in, the heavier the tin is. If you look at the makers' safety data sheets, you can see the SG (specific gravity) of their antifoul - the bigger the number, the more copper oxide it contains. I use International Micron, and leave the boat afloat for 2 full years between recoating.
The crucial thing about antifouling is that you must apply enough of the stuff. I know it's expensive, but lifting out is also expensive. On balance, it's much cheaper to apply a generous amount of antifoul and get it to last 2 years, than it is to lift the boat every year. I apply Micron by brush, to get a good film thickness, and apply at least 2 good coats, with a third coat around the waterline.
As for deals, the best savings are to be made on liftout costs. Many marinas offer cheaper liftouts in summer, when it's also much nicer weather for antifouling. My boat is being lifted next week for its 2-yearly antifoul and polish/