I want to say for a small order like that it'll be quite a lot. I actually went back and checked for you, and they'll charge at least $38 to ship only three birds to you (they consider this an extra small shipment), and I don't remember - I also live in South Carolina and ordered from Metzer about two years ago - if that is in addition to any other shipping charge. Although now that I think about it, we paid about $100 for six animals, so I do think they added some shipping on top of the small order fee. So, if you're determined to get only three animals you're probably looking at about $50 in shipping at least.
I have a question for you, do they have to be Pekins/ducklings? I actually have 3 Ancona drakes that I have to get rid of. Unfortunately they have a bad habit of ganging up on the ladies in the flock, and since I already have a couple of drakes that I'm keeping, that overbreeding was becoming a problem. They're about a year old, and would need a fair bit of socialization since we didn't really raise them as pets - which your desire for males sounds like that is what you'd like them for. However, their broodmates will come up and hang out with us when we sit outside and offer treats, so I have no doubt that with some work these boys will make good companion animals. Maybe not lap ducks, but if you'd like some birds to hang out with in the yard and spoil, they'll be more than happy to oblige. Depending on where you are in the state, coming by and grabbing them from me may be cheaper than paying the shipping cost.

I live in Saluda County.