That's possible, however there are better solutions.
First, do you already have the OS? If not, that's not going to be cheap.
Second, if it starts getting used a lot, your upstream bandwidth will be maxxed out decreasing the speed you get.
Third, it's just another server you're going to have to manage and take care of.
Rather than doing that, you may want to consider getting them all web hosting accounts. It sounds like this is going to be for more than 1 website, if so, contact a web host and tell them your situation. Their sales department should be accomodating and get you a discount on multiple orders.
By getting web hosting from another company, they will deal with the server, uptime, hardware, etc. They will have much more upstream bandwidth and so your connection won't be effected. Last, it's just a convenience to have another company manage everything for you.
With all that said, depending on how technically knowledgeable this is, it could be a great experience. Again, I don't know where you stand in terms of knowledge in this area, but if you've never done it then you may want to try it just to learn how things work.
