Home HVAC cost?

Our outside central air unit went out like 15 years ago. We've been using a window unit ever since. I was fortunate enough to be able to afford one for the bedroom very recently, due to a sale on it at Wally World. Online only, 100 bucks off for an 8K BTU. Perfect for the bedroom and master bath. We swap back and forth between the bedroom and living room, because I shudder to think what the electric bill will be for two, much less one. We'll find out soon enough. I've been getting estimates off and on for a new HVAC system. One wanted 14K for a complete system. In a double wide. LOL I politely said no.