A 767 cannot be flown to Spain and back from Andrews for $375,000. Got to be more than that.
It's a 757. With a quick Google search, I found that it charters for about $15,000/hour.
Rounding up, it's about 4,000 miles from DC to Madrid, and at 500 mph, that's 16 hours, round trip -- or $240,000.
I don't know what the Secret Service cost, but it looks like $375,000 is in the ballpark.
It was a 757, but you've got a valid point nonetheless....