If your going to go with these Triads, you don't want to mix them with anything else. A full Triad system would be most excellent. Polk quality isn't in the same league.
How about these InTheIndustry? I can't access my Triad price guide.
http://triadspeakers.com/products/icb8lcr.html
I will gladly give you pricing on those, Mazer, and please don't take this the wrong way, but I cannot endorse their usage @ all.
Here's why:
My company has done two Triad Theatres (one with their InWall Bronze/4 Omni & one with the InWall Silver/4 Omni) and tried one pair of InWall Gold. In short, they were the most dissapointing products & company I have maybe EVER used. No joke. I hated the Bronze so much that I replaced them for my client @ my own expense. I could not let a system that I designed, installed, & recommended sound like that. After I ripped them out I litterally threw them away. There's NO WAY I would try to sell something like that to anyone ever again. The Silvers weren't much better (I gave them another shot thinking that their entry level was just bad). The in-wall Gold retailed @ the time for $1250 each (if I remember correctly) and were on loan to me from my Triad rep. A pair of Canton 402 GLE absolutely smoked them when we compaired and those retail @ $250 each!
Now if that wasn't bad enough, check this out...... Triad will pre-paint in factory any speaker grille for in-walls and custom stain any in-room product before shipping it to the dealer. "Awesome!", I thought. My client with the in-wall Silvers gave me the wrong Sherwin Williams paint color off the can, which they didn't notice until everything came in. "No problem, it happens", I told them. "I'll order new grilles for you with the right color, no charge". Hey, I'm a nice guy. Besides how much can 5 speaker grilles cost me, right? Ummmm, I found out how much and Triad didn't even offer to buy me a drink first! $60 and change.... per grille.... dealer cost. That's right. I was billed nearly $350 (don't forget shipping to Ohio from Oregon) dealer cost, mind you, for 5 speaker grilles for little, tiny, in-wall speakers. Man of my word, I ate the $350. I just don't consider that a good "value" for me or any of my clients.
I recommended the Omni in-ceilings to "query" because they actually do put put out a good sound for his unique application. We used the smaller 6 1/2" versions in the Silver theatre and I thought they did a real nice job. Not a lot on the low end, but the 8" model should fix that no problem.
Sorry for the rant. To answer your question: The MSRP of the InCeiling Bronze LCR /8 = $750 each