Doesn't your HL already have a bar connecting both front strut towers? I have an 05 and there's a bar. It's not a fancy bar, as the aftermarket ones are, but it's a bar, I'm sure it's strengthening the tower rigidity, and I'm certain it would be LOTS cheaper than an afternmarket fancy one.
Looking for strut bars for your Toyota Highlander? Try the link and you'll find lots of strut bars for different makes and cars. I've bought my auto parts there, they are cheap and performance-wise of good quality.