I have never housed my own snakes together but I have known some that do. Sometimes there can be problems, sometimes there won't be. Housing snakes together doesn't gaurantee something bad will happen but there are bad things that can happen by housing them together that would NEVER happen if they are housed seperatly. That is why people always reccomend not to house them together. You could put two snakes together and they could live their whole lives with nothing bad happen or you could house two snakes together and one could be dead in a week. It's the seatbelt rule. You don't wear a seatbelt because you are going to get into an accident, you wear one to save you incase you get into an accident. You could spend you whole life and never get into an accident or you could be in one tomorrow. So basically if you house snakes together you run the risk of something bad happening but if you don't house them together, then those risks can't happen. When you look at how long snakes live, with housing them together, time isn't on you side for something bad to happen.
Like I have said, I have never house any snakes together myself but i have know people that have. Some of them have never had a problem, but there have been some that have had snakes injured and even eatten.
Why would you want to run the risk of something bad happening to save a few bucks when you have mentioned that you could house them all seperatly.