Local don't have, you may order from oversea and ship over here.
This steps are special made. And it is not cheap, won't able to recover the cost unless we shoot a lot.
Usually we just make do with asking third row to stands on chairs. For four rows deep, the last row will be standing on a table height, it is not recommendable for adults, consider the average weight of an adult
How big of a group? What is the budget? Who is paying for it?
You are actually not really talking about steps but a sort of platform. I have carpenters to do it but it would not be cheap as each set needs to hold a fair amount of weight.
PM me if you need to find out costing.