Oh, sure:
It’s apparently unavailable now, but it was about $30 when I got it. You can get it cheaper straight from China:
… but it will take a while to get there! Depending on where you are, of course.
If you want a bigger antenna than the one that comes with the kit, just look for a 2.4 GHz antenna with an RP-SMA connection. (the “RP” is “reverse polarity,” and it’s important.) It’s the same kind of antenna you’ll see on many WiFi access points and routers.