If his MacBook can handle the entire database so I don't see the need for a SAN (yet). I don't know how much benefit there would be to increasing his systems RAM, but if the database fit's on a laptops HDD, then you can probably get most of it into ram which would make things insanely faster. My guess is upgrading to a 10,000$ box with 64Gb of ram and a 1 + 0 RAID of SSD he could probably get 50x increase in speed which would be ~5k operations per second. Granted he might develop issues with network bandwidth or some other bottleneck, but even just averaging 1k/second represents huge revenue potential relative to the cost of that system. And a back of the envelope calculation should give him a rough estimate of it's value.
PS: Upgrading 10gb Ethernet is not really that expensive now days if he is only linking a few web servers to two databases.
If his MacBook can handle the entire database so I don't see the need for a SAN (yet).
The SAN comes into play when a single box can't deliver the IOPS anymore - remember it's not just a matter of adding SSDs. At those rates you start touching the controller and bus limits. Likewise a saturated 10Gb ethernet link causes a significant interrupt-rate (older cards would bottleneck on a single core) that often exposes interesting corner-cases in your OS and hardware of choice.
I'm not saying it's not doable and I know what SSDs are capable of (we just fitted a server with X25's). I'm just saying that your estimate of $10.000 is very optimistic, add a zero and you'll be closer to home. That's because I still think you'd definately be talking an xfire 4600 class machine and a SAN.
Anyways, this is all speculation. Wheels made some reasonable statements that they have it on their radar and I'm definately looking forward to some real-world benchmarks with a concurrent write-load.