The 45B is technically the matching bookshelf, but it's a big large for a surround. The 35B would be a better choice in my opinion. You need to adjust your budget for speakers, spend $200 on the surrounds, and $500 on the sub. The sub is one of the most important parts of your HT and you can't skimp here, I would skip Polk when it comes to subs. Your subs don't need to match, and neither do your surrounds.
Pick up those 35B which you should be able to get for under $150, and then spend the rest on a SVS PB-1000. This is a very good sub, much better than that Polk, and will get you good accurate bass and sub-20Hz extension.
Denon AVR-1713 | EMP E55Ti | EMP E56Ci | EMP E5Bi | BIC F-12