The BR-2 is a fairly different sounding pedal. I'm guessing there are a few other filters that could be set somewhat similar but I couldn't tell you for sure as it's not something I've tried to do. By accident I did get a similar sound out of the Chunk 00Funk the other day, but it wasn't exactly the same.
The thing with the Guyatone (and the reason it got discontinued) is that it really isn't a very "funky" pedal. But it does have a very distinctive "throaty" or "burpy" filter sound and of course can give very aggressive sounds when paired with dirt as Justin Chancellor does.
If that's the sound you want, you'll likely just have to overpay for a used BR-2.