Is $14,000 to install a gas line and gas furnace a fair price?

I moved into my house in 2023 and have been experiencing extremely high electric bills during winter. An HVAC inspection a year ago revealed that I have a mobile home furnace in my 1200 sq ft home, which was built sometime in the 1800s. Although I added insulation to the upstairs roof in October 2025, my electric bill continues to rise. Last winter, I kept the heat between 62-64 F due to cost, but this winter I've been leaving it at 68 F because I was tired of being cold. My average monthly electric bill is almost $400, and it's clear the heating system is the issue as summer bills are much lower. I do not have a gas line, but I've been advised that switching to a gas furnace would be the best solution. It's been difficult to save for a new furnace because of the high electric bills, and I'm hesitant to take out a loan without understanding the potential savings. I do not want to install another regular electric furnace.