Not a cuemaker, but I'm using housecues for breaking all over the places I am. And sometimes for good fun to show a few funky shots...
First, you could ask what your customer has in mind. Surely not 5+ $ tips.
Second, you want something resembling a medium-hard tip for increased robustness. Pure hard tips are just no fun
Right now there's a huge sale on Ultraskins (search for the threads) that will put the price into a good range. They're also very thick which might increase the shelf life.
Do not choose Elkmasters, they quality varies way too much and they're too soft.
Buffalo Diamond Plus should also be an option.
Not sure about milk duds and their pricing and hardness.
I have used elkmasters, and lepros....back in the day. Nowadays I would recommend Milkduds from Muellers. They hold up to the breaking, and still shoot very well and the cost is reasonable.
DAve
LePro is the most economical decent choice. But I would spend a little more and use the Triangle. Still less than $1 each and with less miscues than the Lepro I think less will pop off.