Because of the risk of disease, it's tough to find someone who will do buck service, and even harder to find someone who will lease a buck or board your does. That means you have to do a driveway breeding. When the doe comes into heat, you have to drop everything and drive her over to the buck for a date. Most people give up with that idea after a year or two because it's a hassle. The other thing is that it's easy to get the timing slightly off. A doe can only get pregnant for a few hours every 3 weeks, so it's easy to miss that window and take her to the buck a little early or a little late. If you are planning to get NDs, they are not as stinky or difficult to handle as larger bucks, so most people with NDs do have their own bucks.
Two schools of though on the bucks companion -- get a wether or another buck. A wether is cheaper, but a second buck is inevitable if you plan to ever keep a daughter from your first buck, so some people just get the second buck right off the bat. And bucks do need companions. They're herd animals, and if they don't have a companion, they will forever be trying to get to the does, even if they are not in heat. I explain this in detail in the book.
You should always have two fences between the bucks and does, whether it's Electronet or woven wire.
ND bucks can reliably breed does by the time they're 6-8 months old. I know there are people
online who swear they've had 2 month old bucks breed does, but I'd like to see the DNA tests to prove it. I know 2 month old bucks will try, but I also know that I've had 6 month old bucks breed does and not get them pregnant. I think most bucks in the 2-3 months age range are shooting blanks.
If you want to see other opinions on this topic, check out this
thread:
http://nigeriandwarfgoats.ning.com/forum/topics/own-a-buck-or-no