Any righteous websites to buy shower niche? i'm looking to purchase a shower niche? any good sites/company anyone...

i'm looking to purchase a shower niche? any good sites/company anyone know of?
How to caulk my window? - house is...
Answers:    No offense but how might you define NICHE, and most especially how it equates to a shower "STALL"?

Obviously within are standard sizes, and custom fabrications one can proclaim online, or in party at a store, but looking online and actually buying from online surrounded by that situation, isn't at all what I'd advocate