Hi-we have what we think is original 1966 day and night furnace. Since we live in southern California and don't need much heat, it was sufficient. Now it appears that the gas valve to the burner is not kicking in and we're cold. We have pilot light and blower working. We were quoted a rough estimate for the part to be $500-$600. I see similar valves for sale for not more than $250. Are we being taken advantage of? And, is it worth replacing this part on such an old unit?
Thanks in advance!

Not really. The HVAC company is going to mark up the part, charge 80+ dollars per hour and a trip charge for their drive time and gas and vehicle expenses. Just like the rest of the people in the united states, their service men want a 401K, vacation days, health insurance and a livable wage. The government is going to take 20% of their profit. And we have to do all of this year after year, feast and famine, based on the weather. Right now, for this month, due to unusually warm weather, we are spending more than we have brought in. Should I go on. :-) It is expensive to do business in America these days.