You could grow them from seed, but they needed to be sown indoors weeks ago. Most HD's, Lowes, and your local nursery will have them in stock soon, they should not be hard to find at all. Check out the link below, this is one of my favorite nurseries in your area.

Here is a link that might be useful: Sweet Valley Farms

I do. Love them. They are a tender perennial, so I dig mine up every year to overwinter. If you are near Maplewood, you can usually find them at the Maplewood Garden Club's plant sale (May 7 - 9).

I got my pentas at Timothy's on Rt 130 in Robbinsville. I don't know if that's near you, but it's worth the drive if it's not. There are several HUGE garden centers within the same mile or so on 130 right there.

http://www.timothyscenter.com/

http://www.amgardencenter.net/