The same player, the same night as grumbling that inspired the it's magic not science post asked one of the local peddlers of gee-gaws and dood-dads related to magic working asked where he could buy a magical sword or if he could be setup with someone who could make him one. He was put-off that the answer was "no, they are too rare and someone able to craft them has better reasons to forge them than a chest of coins.".
Me-thinks the player doesn't get it. Magic items (at least one with oomph) are special. Magic items are not produced by factories or even in a cottage industry, they are special, expensive and risky because they are magic. A magical weapon isn't just a better more expensive weapon, it's a "magical" weapon.
Now of course one could be mistaken into thinking the guy who sells daily fortunes, ingredients for scroll inks, the occasional spell component, or the odd very minor charm has access to an up-scale market with "the good stuff".... well yes and no. "The good stuff" would be an expensive component, maybe a whole potion, or once a year or so a complete scroll. If the merchant had access to "the good stuff" he wouldn't be selling the small stuff as he isn't living in an industrial consumer society producing magi-tech for various markets.
How many Lamborghini Aventadors would ever be manufactured if they needed dragon's blood, the assistance of a demon, an entrapped elemental, a translation of a verse found in a Mayan temple (on the moon) and a years labor from Bill Gates? A magical weapon isn't just the fantasy world equivalent of a $380,000.00 purchase. It isn't even like dropping $7,000,000.00 for a gold and diamond encrusted model of a Lamborghini Aventador, there is no industry to support the creation of magical weapons because there is a constant danger and a unknown element in magic that just isn't there for expensive individual purchases in the modern real-world.
When your computer breaks Demon's don't come looking for your soul. Some of wealthiest, bravest, and most dangerous men in the world don't have to risk their lives and fortunes to get you the parts for your sportscar. The church doesn't threaten to excommunicate you for buying a diamond studded gucci-watch. All of the above are common elements for magical weapons.
That's why magical weapons are not for sale.