IMHO if you are doing less than 100 hrs a year it is cheaper to hire but as with everything in life it is better to own and then have the flexibility - its a choice you have to make yourself and I decided I wanted to buy and I know it dosn't make financial sence but then again flying helicopters for fun dosn't make financial sence full stop!
I went for the Enstrom because it is bigger, safer and I think probably cheaper in the long run when you take into account the callander lifed parts (only the lamiflex bearings on an enstrom) liability of the R22.
The cost price dosn't come into it that much as you will get back about what you pay for it if you don't put too many hours on it.
Maintenance costs seem similar to the R22 and there are a few very good engineers around who specialise in the Enstrom.