We're looking to install air conditioning in our home (~1800 sq feet
single story) in southern california.

It has never had AC so all of the duct work will need to be run.

It is an old home and the walls/ceiling are plaster but there is
excellent access to all of the ceilings and some walls via the attic
which has 20' of headroom.

I am in the process of getting bids and would like some help as to
whether what I am being presented with is fair or overpriced. I have no
problem with someone trying to make a living, but I'd like to not be
taken to the cleaners.

It seems as though ALL bids on this home happen to be high (for any type
of service) because of its beach front location.

Bid:

Install 4 ton Carrier 38YRA w/ matching coil/air handler and duct work
(consisting of 10 drops plus a return)
Install thermostat
Carpenter Subcontracter needed to make duct holes in the lathe and
plaster ceiling.

$8400
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Is this a fair price?

Thank you for your time.