I briefly looked at this while we were shopping for a C-28. There was a C-28 LE with electric cooktop in WA. We absolutely needed propane given the amount of time we intend to be away from marinas.
Didn’t get exact costs just an order of magnitude.
Marine propane stove with cooktop $1,200 to $2,200, propane tanks $120 to $200, safety valves, solenoid and lines $200 to $300, propane locker from RT $???, misc. stuff a couple hundred dollars. Rough guess on labor from WA Cutwater dealer $1,500 to $2,500 depending on unknown labor hours required.
Once the costs for the conversions went over $3k I decided a LE edition boat was not an option for us.
Good luck!