The actual wall would cost like 50+ billion. The current debate is over enough money to build about 55 miles of wall. The current debate is political only; it doesn't involve anything real. It has zip to do with border security. If the prez were anyone else, then compromise would be reasonable. Trump is a crazed narcissist, with all the trappings of a wanna-be tyrant. He's a bad person to compromise with.
There is plenty of history of Congress and POTUS working together. Clinton is one good example; but the classic is Reagan and Tip O'Neill. They agreed on little; but worked things out. Trump won't compromise; and as such is not a legitimate partner in political give and take. He made his own bed decades ago, and brought it with him to office. Until he offers up compromises on some legislation, he'll be thought of as such by thinking people.
As for the wall; it's a symbol, nothing else. Almost useless as a structure, especially 55 miles. By the way, Trump had like 25 billion in wall money and refused it. Then he had like 1.9 bil, and refused it. Now he's stuck with 1.4 bil and is screaming victory. If Dems just say "okay" to any of his demands, another will follow, then others. This is not politics as usual; it's not even politics. It's a one man circus, nothing more. Don't believe me; plenty of the clowns in his own admin think so. A large of proportion of his appointees have quit, those that aren't arrested mind you.