Woke up today to no heat. It's freezing outside & 50 degrees inside.

Furnace guy was just here and got it working again, but it's on it's last
legs. Furnace is over 13 yrs old. I've set up an appointment to talk
to a sales person about choosing a new furnace & I have no idea how
much they cost. When they refuse to discuss the cost of a new unit,
you just know it's going to be expensive All I need is just a ball park
figure. Anyone replace a gas furnace lately? Have any idea?