One thing I would suggest is try to visit some other clubs and talk with some Czech/black sable dog owners about what they like or dislike about their dogs'. I think there are several clubs in the midwest that have members with Czech dogs also. You might have to make a few phone calls to club contacts, but even if you don't have the time to go and vist these people, I'm sure they would be willing to answer a few questions on the phone.
My club is in Western, Illinois, and we have 9 Czech dogs in our group right now. Some of these dogs wouldn't be appropriate for a beginner, but others would be. I mention that because we always welcome people to come and visit. Over the years I have seen a lot of people make bad choices, and the dog, the person, the persons family etc, all suffer. On the other hand I have seen lots of people that have made great choices and wouldn't trade their animal for anything. The latter are generally people that do a little research.
Be a good consumer is basically what I'm saying here. Use the information you gain from visiting the different dog clubs, make some phone calls, or better still try to have some hands on experience before making any decisions. You can rule out certain dogs or blood lines once you identify what you personally like and can live with.
Picking a SchH prospect based on anything other than working abillity can close some doors for you with breeders. That being said though, if you do your homework, there are breeders that do in fact have darker pigmented dogs, breed for SchH work, and would be willing to explain their breeding programs to you.
That's where your friends and your SchH club can help you. Don't be in a hurry, and get some folks you trust to help you with your selection process.