I'm pricing it out right now.
My neighbor just got his quote: $3300.

He's got a .5 acre lot, and a fairly small house.

I'm still waiting for the guy to come measure and give me a quote, but
I have about 50,000 sq ft of lawn. Another neighbor has about the
same lawn as me, and his irrigation system was under $6k.

The landscaper told me I would need 40psi, 16 gallons per minute ( we
are on well water), so I'll have to upgrade my pump and possibly my
tank. But if you already have the pressure and flow you need, all you
have to pay for is the system.

Get several quotes! There are plenty of guys who will quote double
the "right" price, thinking you won't know any better.