any body know how to make acid catalyst in the cheapest way? i found that we can make lye from wood ash..thank you

Very difficult, as is making your own concentrated lye.
Wikipedia has good articles on both:

lye and H2SO4

or do you know other acid instead of H2SO4 that i can obtain in nature remote area..

You can concentrate the acid from car batteries.
Charge them first even if the batteries are dead.

You then have to boil of excess water to concentrate the acid.
As concentrated sulfuric acid has a high boiling point the mixture will stop boiling when it is about 90% pure.
This is dangerous and should only be done outside.
Toxic gas is given off.
Use a regulated heat source to reduce fumes

you can buy it as drain cleaner from B&Q in the UK which I believe is Homebase or some such in the states. It comes in a yellow box and is called 0ne Shot or some such over here. It is at least 90% pure and by memory I think 96% or thereabouts. I just buy it form a chem supplier as I am in a city.