Maximise profits? isn't that another way of charging top dollar for laying cheap poop?? hahaha
If they want the best then they have to pay for it mate, if you were using an acrylic go for a solvent based one like picseal / smartseal / etc, resiblock trade is a water based acrylic and will not last very long, it's not to bad on indian stone though or patio flags as it gives quite a nice sheen, but when it comes to joint stabilization of block paving then I wouldn't bother mate, and I certainly wouldn't charge them through the nose for it as it's only £50 a drum... you get what you pay for