I've seen many converted to oil, but none to propane around here. Cost wise I couldn't help you on that - I just don't know. Converting to oil ... "should" ... be as simple as fabricating a mount for a Beckett (or brand of your choice) burner, and calculating what size nozzle/fuel pressure you need to run to achieve the correct BTU output ... but I've been around long enough to know that things like this are always easier SAID than DONE.
Wish I could be more help to ya. Thanks for the Thanksgiving wishes - same to you and yours
- and good luck on your solution. Someone with more experience on this will chime in eventually. Might be a bit slow around here due to the holiday, but they'll come.