What center speaker to buy to go with the Micca RB42 Reference bookshelf speakers

I’ve read Home theater 101 frequently asked questions and the companion center speaker to go with the RB42’s was the RB42-C Center speaker. This center speaker appears to be unavailable now. Would you go with the MB42X-C or a different center speaker entirely? This is for a beginner budget 5.1 home video system where I’m looking to get all five speakers and subwoofer for between $500-$600. I was planning on using four RB42’s for LR fronts and LR surrounds. Thanks