Good luck! The gifted school where my ds6 goes is definitely out of our financial league -- we get hefty financial aid, and I hit up my parents for some tuition help (who are in a financial position to contribute). There was no *way* we could have afforded it on our own.
And it's a 35-minute drive from home.
But ... we sucked it up and checked it out, and then we made it work.
It's made all the difference in the world for ds6 -- he loves going to school and is appropriately placed. So definitely, go look! You may be surprised at what you can finagle if push comes to shove.
As for bringing the WPPSI with ... maybe that *is* how they do it. Do they have a numerical cut-off? Ds's school did, so maybe the school you're touring just wants to make sure your ds does qualify for admission?
Good luck! Can't wait to hear about it.