If your water heater is that old, I would replace it ASAP with a new one of same type. Who knows what kind of crud buildup is on the inside & on the elements, and it is on way borrowed time as far as suddenly springing a leak. At likely the very worst time.
You should be able to do that for less than $500 (without knowing your exact setup) and see immediate savings. I put ours up off the floor on a (very rugged) wooden stand, on a layer of 1" foam board. Wrapped a layer of 6" fiberglass around it (held in place with taped up foil bubble wrap - looks a little hokey but not all that bad). Added a heat trap at the outlet. It is very economical. Like I say, maybe $25/mo at similar all-in rates.
You should also be able to adapt a tank type heater to another heat source later if you want to, by T'ing off the bottom inlet or drain, and the relief valve fitting.
Yes, the water heater is changing soon, it's just hell trying to get someone to the house because of mud season. I think we've made up our minds to go with an LP on demand unit and a 40 gallon range boiler in the "attic" behind the bathroom above the utility room. The range boiler will be fed by the existing SWH and the wood cook stove going in this fall.