I Helpd an Amdram group for years and they had a similar situations where they hired in an average of 12 radiomics twice a year for their main productions then another once or twice a year they hired in 4 radiomics and although I dont work with them anymore back then they were interested in buying their own and I would manage them, they had a plan to find funding to purchase some and they had bought several in the time I was with them as for their big productions the cost would be around £700 per big production for just the radiomics so it was in their interest to purchase and they had a good working relationship with a local school which would have hired them for their production also so all the different times that they would be used a year would make it worth while.
what I would say is if you did buy your own is that you need one person who is knowledgable in technical equipment to manage them for you and to store them and to manage any possible hires you may have (good way of generating some income but b prepared for the costs of any possible damage that could be charged back to the hirer) and also buy some good quality equipment to start off with.
