Breezaire & Whisperkool are two units that have been around a long time. You might consider looking in the advertising section (the last few pages of the Wine Spectator) for wine coolers.
However, I really think you should check with a local Commercial Refrigeration Company, and ask for their suggestions. Although you can get overnight service with Breezaire & Whisperkool, having a local service company is a real plus. Also, I think too much is made over having a cooler specifically for wine. It's refrigerated air; and I think humidity is not as necessary as you are made to believe. After all, humidity has no effect on glass, it's bad for labels, and as long as your bottles are horizontal, one end of the cork is always wet, making cork shrinkage a non issue!