I recently purchased the 256GB SanDisk Extreme model. As my motherboard lacks SATA3, I also picked up an PCIe SATA3 card (IOCrest Asmedia ASM1061). While not as fast as Intel's on-board SATA3, it seems to be the next best option without forking out on an expensive RAID card.
The following are two benchmarks of this SSD with this card in my PC. The left image is the SSD straight out of the box. The right image is after a few days of regular use. I'm quite a heavy multitasker and have been using VirtualBox on it (Virtual PC running Windows 8), so it seems this has had an impact on the write performance, just something to beware of like with other SandForcce based SSDs:
Either way, at least the read performance remains the same and I'm still very happy with its performance considering it was the second cheapest ~240GB SSD I could find at the time (Â£157 on Amazon UK.)
For anyone curious on how the Asmedia 1061 card performs, the following is a benchmark using the '0xFF Fill' mode, which basically tests any SandForce-powered SSD in its "best case" scenario: