I have recently been through the same decision process before I bought my third R22. Option 1 means it is never around when you want to use it plus the increased maintenance costs plus low utilisation by the school and the risk of expensive misuse make it a non starter in my opinion. Two of us decided option 2 was the best bet, but despite advertising widely over a period of several months only succeeded in attracting wanabees without the necessary funds. So in the end I wound up with option 3 which is the only one that really works (however with an R22 again).