I'm interested in purchasing a Seamaster 300 Co-Axial. What online dealers would you go to purchase this watch, or would you visit a boutique shop for this purchase? What is more economical?
I'm pretty sure there are no official online omega dealers. You would have to go to one of the few remaining ADs or a boutique. There are also numerous reputable dealers/sellers on these forums.
Would you buy a watch from these websites? http://www.authenticwatches.com/omega-seamaster-23390412103001.html#.V1PIV_RHanM https://www.watchmaxx.com/watch/omega-seamaster-300-master-co-axial-41mm-men-233.30.41.21.01.001
I have bought from both with no problems. But first, I would check the classified ads in this forum. I always look here first.
I haven't had first hand experience with either but I've heard of many bad experiences with authentic watches. Like ctpete, I'd look on these forums first.
I know of a couple of folks that have purchased watches from Authentic Watches with no issues. That being said, check the sales section here as others have said, or reach out to @Kringkily who is a member of the forum. He comes highly recommended by a lot of people here. He may be able to find what you are looking for.