I like the Kiky X-Series PS1 & PS2 to USB adapter. It's been working with every OS since the pre-SP1 edition of Win XP. Works perfectly with both PS1 & PS2 controllers. No drivers required. In fact, IIRC it didn't even come with a driver disc. I purchased one and liked it so much that I went back to the store for another.
I have two of these exact units. Bought them at Microcenter, about 2007-2008, for $15 each.
As for authentic, first-party Sony PS1 & PS2 controllers? They're basically indestructible, (Sony built them like tanks) and there are infinite numbers of them. Try Amazon, eBay, the GameStop web site, Play N' Trade, Games X-press and even goodwill. They're out there - Sony must have produced billions of them! Have a local/regional comic book/anime/toy & collectible show near you? Try that. I picked up two silver, brand new, authentic Sony PS2 controllers for $8 at the toy & collectible show in Parsippany, NJ. If they're available in my neck of the woods, they're available in yours.
I acquired two brand new units (not in box) for $4 each at a local game/comic book/toy show.