Lightsabers seem to be somewhat labor intensive to build. And, from everything I've ever seen or read, a Jedi was responsible for creating their own. Anakin Skywalker is shown to have lost several of them in the films, which I would assume result in a lot of lost time rebuilding new ones. Was there ever a point where they were mass-produced? That is, could you ever go to "Crazy Yoda's House of Lightsabers" and just purchase one? Or was building one from scratch the only way of ever procur
They are not usually found in other places such as a store or such. They are mainly used by Jedi's or Siths so it's not common for you to find it in a store. According to the Star Wars Wikia about lightsabers during the Clone Wars there as at least one that was sold in a store.
" At least one lightsaber was sold at a storefront for credit 500,000 at Pons Ora during the Clone Wars."
↑ TCW mini logo Star Wars: The Clone Wars – "Missing in Action"
They were however mass-produced or at the very least common as it states here in the wikia
"When the Clone Wars began, Jedi lightsabers experienced a change in focus. Rather than being created as a meditative exercise, heavy-duty lightsabers built to stand up to the rigors of war became the norm."
So you can assume that they were mass produced for the Jedi's at around this point. Previously they had only been for meditative purposes and not used for war.
After the Jedi Purge they were not that common though...
Rhinann: "The weapons of the Jedi were destroyed along with the Jedi. There are rumors that some lightsabers remain in the private collections of the extremely wealthy. But the only one that I am certain truly exists belongs to Darth Vader, and I doubt he'd part with it willingly."
Pavan: "A crystal then. I'll build my own. It'll be more in tune with my—"
Rhinann: "Adegan crystals, as well as Corusca, Ilum, and others, are under strict trade and commerce interdiction, per the orders of Emperor Palpatine."
Pavan: "I'll grow one, then."
Rhinann: "That may be possible. It will take some time, however, to assemble the necessary equipment and materials."
―Haninum Tyk Rhinann elaborates on the illegality of lightsabers to Jax Pavan
This implies that the necessary equipment and materials are rare at this point.
So overall before the Jedi Purge but after the Clone Wars there seemed to be a lot more than there was before the Clone Wars.
It seems that there are a very large amount of lightsabers, as shown in the second movie/episode Attack of the Clones, when Anakin Skywalker and Obi-wan were in the arena, the clones came to the rescue along with some jedis. They Anakin and Obi had lightsabers tossed to them. To me it seems like there might be a very large source of them, the most valuable resource needed is a Crystal.