When I began my pastoral ministry in 1981 the little church had a terrible sound system. There were about half-dozen microphones sitting on a ledge behind the pulpit area. Only one worked, sometimes. Of course, this was before cordless mics were easily available so I always felt I had a rat's tail following me around that I had to handle. To make matters worse, occasionally a trucker's CB radio would come blasting out of our sound system even though the church was a good mile off the highway. There's few things worse than asking the question, "What would you say to God today?" than to have a trucker shout out "Hey, good buddy." Actually, there could be many worse things, but fortunately they didn't happen.
We eventually purchased some new microphones, but that only solved part of our problems. Things improved greatly when we decided to have a professional sound company install new equipment in the church. They ran new wires (we found out the wires someone in the church had ran were wrong) and pointed out the system that was best for our facility. Surprisingly, it wasn't really that expensive. In fact, it was probably less costly than if we had continued to try to fix it piece by piece ourselves.
My voice carries well in a small church auditorium, and I seldom need a sound system to be heard by most people. However, having a quality sound system lets me not have to worry about being heard and ensure that everyone can easily hear me. Over the years I've had many senior saints express their thanks that they could hear and understand everything I said and their frustration that wasn't always the case with other speakers. If a person can't hear what's going on eventually they will just stop coming to church.
Smaller churches often want to do it yourself when it comes to their sound systems. That's probably a mistake unless you have someone trained in how to put together the right system for your situation. You run the risk of getting the wrong equipment, setting it up incorrectly, and having the expense of having to do it over again. At the very least, get an estimate of what the right system would cost. That won't cost anything, and you might find it much less expensive than you thought.
The other aspect of a quality sound system is having people who know how to operate it. I've been amazed at churches with very good systems that have no one who really knows how to run it properly. Or, they have one person who does know but no one to fill in when he or she isn't there. I know I'm in trouble when I go to a new church, ask for the speaker's mic, and no one is sure where it is. I'm in worse trouble when the person who gives me the mic tells me the regular sound guy isn't there, and he's going to do the best he can.
If you're going to invest in a good sound system, invest in training several people in how to properly use it. Any system is only as good as the ones who operate it.
Along with this, the church's sound system is not a toy to be used by anyone who wants to use it. I advise keeping the system unavailable to those who have not been trained in how to use it. You don't want people coming in during the week playing music on the church's sound system, or changing the settings on the mics and volume. I've seen sound people spend 10-15 minutes trying to get everything back where it needs to be to function properly. Lock it up if you have to protect the church's investment.
Good sound systems are not cheap, but they don't have to be so expensive your church can't have one. Get the best system you can afford, train people how to properly use it, and it will be add much to your church's worship experience.