I don't think that it's as important to match them as it used to be, depending on your electronics. My Pioneer receiver from over three years ago did a great job of auto equalizing my speakers to make the front soundstage pretty seamless. BTW, my speakers were supposed to be timbre matched, but they sure didn't sound like it to me.
So, my advice would be to get as close as you can (provided budget and availability), but it's certainly not the end of the world if you can't get something exact.