New HVAC Shopping Advice

Long story short recently bought a house with a 17 y/o HVAC system that recently started leaking. Called a tech thinking it was clogged but there was no clog. They explained that the HVAC is old and it is probably time. Had the AC running since and we experienced another leak last night.

I was wondering how to shop for a new HVAC system and how to finance such a large purchase. Not sure how to go about this. Getting someone over to do measurements and a quote but I dont want to spend a ton on it either. Thank you for any advice.