To most people who have alpacas, they are a "business", and the numbers they have in their herd sometimes makes it impossible to take the time each one needs to become tame. If you get them young enough I think it's easier to tame them, but for the most part, alpacas enjoy being in the herd, and don't really enjoy human contact. We used to raise them (sold out in 2006) as a business, and had mostly bred females on the farm, so not wanting to stress them out, they were mostly left alone.
If you have just a couple, or even 3 or 4, it isn't to bad, but when you get a pretty good herd going, they can be alot of work. I think sometimes people don't understand what is all involved in taking care of alpacas. I've seen a couple people who have them, and simply do a Safeguard oral paste for wormer. There is actually more to it than that..............
depending on the area you live in, so that should definately be part of your research. Alpacas are highly susceptible to meningeal worm from white tail deer, so if you are in an area where deer congregate or pass through frequently, you should look into the requirments needed to keep your alpacas safe. Meningeal Worm effects the nervous system, and can be fatal. I've seen first hand, alpacas effected by meningeal worm, and it's not a nice sight. The best known prevention is an injectible ivermectin wormer (we used Dectomax) every 30 days. Safeguard paste is also used, and I think I did the Safeguard 1x per season, spring, summer, fall, and winter.
Another thing to be aware of, is what you feed them, and how you feed them. Alpacas require a feed lower in copper (I believe that's it), and some folks I've seen feeding a horse feed mix. Be sure you have a feed specific for alpacas (or llamas will work) because you can get copper toxicity if you overdue. Alpacas can also "choke" very easy. It will most likely happen when they are eating their grain, if they are eating to fast, or if they are eating it low to the ground/on the ground. We always had our feeders set up higher, and put rocks in the feeders to slow them down. I remember the first time I saw one of our alpacas choke........it was the scariest thing!
If I remember correctly, even having fiber males, if you have enough to process and sell the yarn, can be considered a "business", and can be used as a tax deduction. For us, the tax deductions were well worth it, and greatly missed! Check with your accountants on that to be sure, but I know when we started in the business, if you processed and sold their yarn as a business, you could get the tax benefits.
Best of luck with your decision, and have fun!