Are you meaning the hardies or the houseplants? The hardies (cypripediums)come in pinks, white and yellows, mostly. Many need colder temps than we have around here but there are 3 or 4 kinds that will grow here. The housplant/tropicals (mostly paphiopedilums) and come in greens, whites, maroons, pinks, yellows and some weird crosses. The tropicals tend to be heavily spotted and their leaves are as well. They bloom for a few weeks. The hardies are quite expensive and can be very tricky to grow, unless they are poached, and those inevitably die. The houseplant type is usually in the same price range as other orchids. They are fairly easy to care for.

To elaborate a bit on Tamelask's reply, most of the artificially propagated stock of hardy Cypripediums available from online nurseries seems to come from northern populations. I had some art. prop. Cypripedium parviflorum and C. candidum that grew wonderfully up in Michigan. The C. parviflorum was from Minnesota, I think. Anyhoo, once I brought them down to North Carolina they struggled for a few years and then gave up the ghost one hot July.

The best Cyps for our climate are probably C. acaule if you can find a legal southern source and Cypripedium kentuckiense.

I grow several species of Cypripedium in Southeastern VA, and have had my share of successes and failures over the years. The biggest problem here is our climate - long, hot, humid summers and capricious winters during which the long warm spells often cause Cyps to break dormancy early, only to be threatened by late spring frosts. If I'm not mistaken, Lewisville appears to be more inland than we are, as well as in the Piedmont region, which would imply better drainage and perhaps more stable winter temps, which would be an advantage in growing these plants. I use deep, open mulch (like white pine needles at least a foot deep) in winter to keep the plants as cold as possible for as long as possible, and spray the plants with fungicide after periods of heavy rain in the summer and early fall to combat infection. On balance, the so called "hardy" slipper orchids require a lot more life-support in this region than do the tropical and temperate Paphs and Phrags I grow in my kitchen window and greenhouse!

The species that seems best adapted to our region is C. kentuckiense; mine has dones very well for several years, along with a couple of its hybrids. I also have high hopes for C. japonica, based on info from the National Arboretum in DC. I would not recommend C. acaule; it does occur naturally in this area, but its soil demands are so specific (requires and extremely acidic, sandy soil and a perfect balance of summer moisture) that I've never experienced or even heard of a locally successful transplant in the long term. If I were going to try it again, I'd go with a seed-raised plant, and as far as I know, the only dependable source for these is the Vermont Lady Slipper Co.; they are always sold out when I think of checking their website.

The best source of cultural info I can recommend, at least for the eastern US, is Dr. William Mathis's book on the cultivation of Wild Orchids - he also raises and sells Lady Slippers, along with other genera which are adapted to growing in the area (Wild Orchid Company). Other good sources are Hillside Nursery, Raising Rarities, and Roberts Flower Supply, all of whom have websites with good info available. The main supplier to most US retailers at the moment seems to be Frosch in Germany, and the prices at which they resell these plants vary wildly, so I'd compare those as well. I have to say that I have not had good luck with Cyps purchased at Plant Delights, which is otherwise one of my favorite places from which to buy plants; on receiving the Cyps from their wholesaler they pot them up in their standard composted bark mixture, which is, I believe, too heavy for these plants at their most vulnerable stage of development. The best plants seem to be shipped bagged (which allows the horizontal roots to maintain their preferred orientation) in a barely moist peat/perlite mixture.

Here's a link to one of several posts I did on my blog last spring involving Lady Slippers and other hardy orchids, in case you want to take a look.

Here is a link that might be useful: Transitional Gardener Blog Orchid Post