I have only seen them in wood. I am guessing maybe not metal ( conductivity ) and seems like it would be hard to achieve cost savings with concrete if possible?
I would def use treated wood ( may be code any way but if you have a choice for longevity. And then concrete the base in. There are coatings you can add on the bottom of the wood but not sure if that save anything.
Two things to consider, are you on single poles or can you do multiple units at once on the same loop? That might be a way to save money.
Other thing stop consider. Make sure there is no issue with the electric company if you are moving around poles that they will connect onto it ( it never seems to be a straightforward thing each time we do it, always some different hoop to jump through but that might just have been me).
Other big thing to consider , the run from the meter TO the home. Typically we have been charge Per foot. so the shorter the run on the home from the meter, the more you will save on the connection. Keep this in mind when you are doing placement of poles if there are multiple homes going in and out. Also, if one meter is falling over you are replacing one, might make sense to swap both at the same time so your infrastructure increases over time ( which you might have to do anyways.
My last few additional notes, use a licensed /insured vendor .Get your permits pulled ( might not be able to do without it ) . Make sure call before you dig is located when trenching new lines or you cross check against utility lines on park schematic.
See what makes sense for your specific application.
Also, know the process if you are killing the power on a home with power to minimize the down time for a tenant and def keep the weather in mind depending if you are pre planning an outage.