It probably depends on what you buy and where you are in your building of a collection. If you're talking about guys that shop at a big box store or use mouth calls, then they are going to buy more than someone that buys custom box calls. Very few ppl will spend buy more than one $200 call per year.
I'm in the middle. I buy one expensive call and several mouth calls each year. However, I will not spend more than $5 per mouth call and the total is less than $100. Imagine I will stop buying anything other than mouth calls in a few years. I'll have about three of each type by then and not need anymore by any stretch.