<font color='#000080'>I ALWAYS recommend trying to get a voice-matched center speaker, but if you can borrow the speaker and it sounds decent, then consider buying it.
The Axiom VP150 is an awesome center channel speaker, but even the VP100 woudl be a good pick for you. You're talking a bit of a price difference though.
Consider, however, that nearly 80% of what you are listening to and focusing on in home theater comes through (at least partially) the center channel.
You might want to matrix the center until you can afford a matched speaker. Or buy the Polk and use it as a stop-gap.</font>