I put the stainless tip from Wal-Mart (<$20) on my 4R. I think it looks better than the Valor (its slightly angled rather than flat at the tip). It's holding up well after going through last winter's slush - still shines up clean and it fits over the stock exhaust perfectly.
The 05+ humped rear spoiler probably was an attempt to minimize the rotten exhaust smell issue. The hump catches air from over the roof and forces it downward behind the rear of the vehicle.
It doesn't do much at slow speeds though.
I read an article recently that was about shoreline erosion near where I live and as an aside it mentioned that sea levels at certain times in the past had been hundreds of feet below where they are now and hundreds of feet above as well. The present eastern Virginia coastline used to be dozens...
Seems like it ought to be possible for the dealer to set it up for you for the right amount of $$$.
Are you planning on ditching the separate key fob with the control buttons? If so, aren't you going to miss the back window down control?
2005 SE V-8 4WD with rear spoiler, DRL, Home-Link and floor mats........$26,500 brand new. List was $34,7xx if I remember right. That was end-of-year sale including $3000 Toyota cash back. I've seen used ones for sale recently for thousands more than that.