Stopping Illegals from Mexico?

If the US paid the illegals who try to come into the US the money spent trying to keep them out--Border Patrol, fences, US military now, other who knows how many agencies--it'd probably save everyone money!
How? Buy more Mexican exports/products to create more jobs. Encourage more investment by US firms.
Obviously, this solution would be complex--but it would have to work better than the present one!