So it took me weeks of research to find what I wanted- an 18" wheel that was 2-tone or accented, something with an old school feel to it, and I didn't want it to stick out past the edge of the fender (I was going for esthetics).
The most difficult issue for me was offset. My truck can with 18" TRD rims, which have an offset of 60mm. This is by far the largest offset I've come across. The Rock Warriors are 50mm offset (which I considered).
Unless there is something I've missed, here is a simple explanation- the further the offset number from your factory wheel, the more the rim will stick out past the original. Keep in mind, you're looking for the difference between the new vs. original.

Here's a handy chart > http://www.metric-conversions.org/conversion-charts/length/millimeters-to-inches-conversion-chart.pdf

So the easy part was the bolt pattern - 5x150. There are plenty of wheels out there that will fit that pattern- it's the offset that is tough. I found some nice wheels with 25mm and 35mm offset, but nothing (that I liked) larger. The 35mm offset wheel I chose sticks out .98 inches past my old TRD wheels- which I am okay with; the 25mm rim would stick out 1.37 inches past factory (more than I wanted).

I also found there is a significant price difference between the tires I wanted. I had BFG All Terrain 285/65/R18 on my old TRD rims. I switched to (same brand/model) 275/70/R18. In my case the cost difference was $65 per tire, and the actual size difference is slight.

Here's a handy calculator> Tire Size Calculator - tire & wheel plus sizing (http://www.1010tires.com/tiresizecalculator.asp?err=98&rsn=cde-no-cde-gen-by-svr)

I made my purchase through Tire Rack (I almost went through Discount Tire, [free shipping!] but they went out of stock with the one wheel I wanted) as a complete package. Everything was in stock and it was delivered in three days, mounted, balanced and ready to be installed. A very good experience with them, they even called me to make sure, since it was not a stock tire size, that I didn't make a typo.
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The best part- I wasn't really sure what wheel I wanted when I started, but I couldn't be happier, and I think they look great.