Hi friend,
First I should ask, what's clustering points? Fail-over and load-balancing.
Not in VMware vCenter, on any clustering system, resources are shared between nodes. You need to share virtual machine's configuration and VMDKs.
Absolutely, you need to shared storage to configure clusters and use clustering abilities.
About SQL performance on vMotion, based on your hardware specification and especially your network bandwidth, vMotion can do migrate VM to another host faster.
You can use flash memory as local storage for store ESXi files and configuration and mix your SAS hard disks to shared storage by VSA, OpenFiler, FreeNAS and etc.
No need to buy expensive hardware for small scale environments.
BR