Help needed for vintage constellation

Hi guys, I’m new to the forum and also new to vintage watch collections. Have been looking around for a 1960s Connie for the past weeks.

Went to Sydney city today and saw this 1966 stainless steel Connie in original box and paper (saw the box not the paper though). Seller is a vintage jeweller shop and has been around for decades. He told me that the movement for this watch is 501cal, but isn’t the 501 is for the early 1960s models? Maybe he meant 561cal?

Can someone help me check if this is an authentic watch? And the seller is asking for $3800 (~$2700 USD) with 18mth warranty. Is this price too high?
Thank you very much in advance!

Welcome @anjing0406
As @ConElPueblo says, nice looking pie-pan dogleg Connie and the bracelet is a bonus.
Some folks put a premium on a ‘Turler dial’ - I don’t but that is personal preference.
The box may be an Omega Constellation box but is for a much later watch.
You would need to check if the papers go with the watch - and that it has the correct movt cal.
As the watch has an 18 month warranty it’s presumed it has had a full service - again you should seek proof of this or the watch will need a service (regardless of the warranty)
The price does look outrageously high on the face of it but if you add up the likely price of the components if you were to buy them separately on the open market; $1,500 for the head, $200 for the bracelet and $300 for a service, then you can see the kind of premium you are paying for buying retail - their margin will be much greater of course.
(You could be lucky and find a watch like this with bracelet for sub-$1,500 but they are few and far between nowadays)
If you have the cash and don’t want to wait, try and and bargain them down to as near $2,000 as they will go.
(Note: BORs are great but if like me you have particularly skinny wrists they can be problematic and you would want it adjusted by a watchmaker)

It does look a nice example.
Some good comments above, I was going to say $1800 - $2000.
I expect though you might have to go a little higher as that is quite a reduction.
I am always of the opinion it is worth paying a little more for quality, especially when you don’t have time to research,
Good luck.

It does look like a very nice example. Hopefully the case back is in equally good condition. There are plenty of fake BORs about; not by any means saying this is one but it is worth checking the numbers on the clasp and endlinks, the latter commonly 70 or 570 (most of the repros aren't numbered). As @ConElPueblo has said, it's still very expensive indeed but worth considering if you are cash-rich, time-poor and want a good pie pan without delay.

As pointed out you have to decide if you like a double branded watch,
here a non-Turler to compare (picture taken from https://omegaforums.net/threads/vintage-constellations-show-and-tell.19186/)