PS: Upgrading 10gb Ethernet is not really that expensive now days if he is only linking a few web servers to two databases.
EDIT: To give you some idea what flash can do http://advancedstorage.micronblogs.com/2008/11/iops-like-you... (Granted, it's a stupid video, but 150,000 Read IO's and 80,000 write IO's and 800MB/second of bandwidth on two PCie Cards in 09 / 10 with fusion IO doing the same type of thing today).
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.