Just so you know, you may not have to wait for long to see Valgrind working on Mac 10.9 a.k.a Maverick. As there has been some success according to this bug report.
It is my opinion that there are currently (as of 15th November 2013) no Valgrind alternatives for the Mac. There are some to keep an eye on though, namely Clang which has both AddressSanitizer (works on current macs) and MemorySanitizer (macs not supported yet).
There are suggestions to use Xcode's Instruments, but I did not find it useful at all.
