My question involves landlord-tenant law in the State of: California

Please help. I know nothing about home maintenance and would appreciate some advise here.

We have sliding mirrored closet doors in our bedroom. Last year the mirror on one door cracked when it went off the rails and fell. Maintenance staff took the door away and we did not bother replacing it.

I always assumed the doors were made of wood. Last week I decided to replace the closet door and telephoned my landlord for a cost estimate. He claims my closet doors are actually custom made aluminum doors and the cost to replace just the cracked mirror is $500 ! He further claims that we cannot go with Home Depot or Lowe's but with a smaller vendor that he contracts with to replace the cracked mirror.

When I checked online I found that aluminum doors are indeed more expensive. However, prices online include the cost of the closet door and not just the mirror ! He also would not give me a valid coherent response as to why we cannot get it replaced by Home Depot or Lowe's but have to go with his particular contractor ?

Finally, he claims it is my responsibility to replace the mirror fully. Although this was not wilful damage on my part I did not contest this. However I don't want him to get brand new closet doors on my dime. Is there anything I can do legally to ensure that the costs he's charging me are legit and fair and that he's being truthful in his claims that Home Depot or Lowe's are not able to replace the "custom fit closet doors" ?

Please help. Thank you.