The Platinum could mean a variety of things, but it typically included a Platoon transformer, upgraded internal wiring, caps, and rectification. Plus, it could mean better connectors.
You did good on the price because you may be able to get up to $2k for it. However, there is one big "if".
If the work wasn't done in the last few years, then the driver board probably want replaced. This will have to be done soon because the existing board is nearing the end of it's useful life and t some have been showing issues. You'll still do fine financially because you got it so cheap... Still more than double your money depending on what was done previously.
Call Steve to get more details on that exact serial number.