I'm impressed with your speadsheet - you've gone to a fair amount of trouble with it.
It's quite surprising to see the figures presented like that.
I can't comment about some of the prices there, but for OBA, if you go there for PPL training (rather than just buying hours like it appears that you have calculated) then some things are included: flight test, flying instruction, accomodation. I see you've even included the cost of a bike (I took a pucture repair kit with me, and repaired an abandoned bike and rode it)
The Visa process for the US is a real pain. The form filling, the queing for hours, and even travelling hundreds of miles to get to the embassy. The 'interview' after all the wait is a complete farce.
I got good instruction at OBA, and had a good laugh with the people there.