If money is not much of an issue, I recommend Heat wave custom suits located here in Santa Cruz right by campus. They make custom fit 10mm farmer johns with 20mm core and attached hood. Cost roughly around 700 but all of my friends own one and they have no problem getting cold and definitely worth it. I want one myself eventually. I also attend UCSC and I use a 7mm Oneill J-type for all my monterey dives. Awesome!
Personally if I was going to spend $700 to have 20mm of neoprene at the core, id just go buy a used/value dry suit. Imagining the amount of lead, and thickness of the suit just doesnt seem like something enjoyable.