So my parents' central A/C unit finally died last night after about 20 years. The repairman came out and told us that the cost of repairing the unit is high enough to justify purchasing an entirely new one given the age of the existing one. Makes sense... But where do we purchase a good one inexpensively? Is there any place we can find reviews, energy rebates, etc.? This is all for a home in Virginia btw. Thanks!