Dimitrios Paskoudniakis wrote:

... I want to know if someone in the group knows which is cheaper (per BTU)
- oil at $4.50 per gallon

That's $4.50/(0.8x1.3therms) = $4.33/therm, burned at 80% efficiency.

or heat pump at $0.125/kWh

That's $0.125/(5x0.03412therms) = $0.73, with water source heat pump
with a COP of 5.

... as well as the cost to convert

The ground or well loop may be the most expensive part of a heat pump.
A 3-ton 5-COP Climatemaster Tranquility 27 box with a pump and blower
and heat exchanger but no loop costs about $5K and uses less power
than a toaster.

Nick