Well, if the cost of living at the new location is less than where you are now, that offsets the pay loss some.

I guess my advice would also depend on if you're married, have kids, and what your lifestyle is like. If you're used to living at your previous means, then taking a 40% pay cut would require a bit of a lifestyle change. Most people wouldn't choose to make such a change.

I guess it also depends on your preference between working for someone and having your own startup. I think you can do a startup without killing yourself.

Another thought: A 10 year old company probably isn't going to give you equity. But, with their first in-house coder, they might get the web-app/product bug. Maybe you can negotiate equity rights to any product/spin-off that results from your work.