Let Americans waste their money. Yes, THEIR money. I can't believe they actually thought some other country is going to pay far that stupid wall. 
Let Trump spends his money on that wall. Such a crazy idea could arise only in his sick head.What if Trump hires and fires thousands of contractors to build the wall and does not pay them for their work!!
Or he funds the wall by himself and goes broke
I don't think he'll ever fund it with his own money. More likely he'll just get people to build it - and then not pay them. He's done that before and wouldn't have paid the contractors had it not been revealed during the campaign. Abominable.
Last I heard in the news, it was a Mexican company who said they'll build the wall. Maybe that's how Trump will get Mexicans to pay for it? "Oh no, I'm not paying you, that wall is to keep you out of beautiful Murica."