Much like Fuzz Faces and Tubescreamers there are a million clones ot there these days...I really like the Analog Man version (Beano Boost) and the Thro Bak (Strange Master)as well as a few others. Just look into a version that comes with quality parts as well as the correct (or at least correct style) parts.
Keeley makes a great clone called the Time Machine Boost. Check it out! Analog Man also makes a clone, but I've never tried it before. It's the Beano Boost.
Good luck, and let us know what you end up going with.
My clone J/k. Rangemaster is my favorite pedal. As long as the resistors being used are 1% metal film to reduce noise, any clone will sound very similar.