What else is there than just the SEER rating?

all electric or gas/electric?

Coastal or inland?

Size?

Post more details on exactly what builder or dealer is proposing.

IMO

Electric. I will ask the builder for more information and get right back. Inland.

You are not going to see much difference in the operating costs with a difference of one point increase in SEER rating. It is highly unlikely you will ever see a return on investment on the extra $850.

Post the model numbers of the two systems. This will help determine it the extra money is buying a better system in order to justify the extra money. Be aware most builders make a lot of extra profit by over charging on upgrades.

"You are not going to see much difference in the operating costs with a difference of one point increase in SEER rating. It is highly unlikely you will ever see a return on investment on the extra $850."

Agree. However, the higher efficiency units tend to be better in other ways also - quieter, better casework, additional features, etc.

I agree. That is why I asked the OP to post the model numbers so he /she can get opinions if the extra $850 is worth it or not.