$ 2000.00 is bit lean for decent speakers, but I can get you close. In a way I am not may be the best to advise, as I don't shop for speakers. I design and build my own.
However I can give your a very solid recommendation, the SALK BMR monitors
designed by a fellow member here, Denis Murphy. These are thoroughly well designed speakers, that measure superbly. I don't think you will need to replace these, probably ever. Dennis has had the courage to actually market his design. I did it once only to have the drivers discontinued by the manufacturer after the first production run.
As far as the center, the issue of matching, comes down to error matching, to make sure all the speakers are as lousy as each other and lousy in the same way.
Unfortunately center speakers are hard to design and most hobbled from the start because they lay out the speaker with tweeter in the middle and the drivers either side.
This creates extensive vertical dispersion and poor horizontal dispersion, which is the opposite of what is required. So centers need to be either coaxial designs, which I prefer, or three way with the tweeter above a midrange, and woofers either side. They do not have to come from the same manufacturer, or even use the same drivers, as long as all the speakers are really good speakers in every aspect. I use speakers that are MTM right and left, and use a coaxial design for the center. But everything combines to work with seamless synergy.
So as far as your speakers are concerned, I would get the left and right speakers upgraded, and if you get the itch to upgrade the center later, which you probably will, we can advise you then. Good center speakers are far and few between, and I have to say that they present a huge design challenge for multiple reasons.