How do they come up with these numbers?

question mark

President Obama wants 3.7 billion

Senate wants 2.7 billion

House wants 1.5 billion ….

to address the crisis on our border.

How do they each come up with their numbers?  Good, smart analysis after a serious scrutiny of costs and best deals? or pull out of a hat?

I hate to be such a cynic, but I think they all just pull the numbers out of the hat without regard for what is truly needed, how best to spend the money and how best to manage the money taxpayers give them.  I want to do what we have to do — but I need more proof that their (President? Senate? House?) numbers are wise and needed.

What do you think?