The 410 "live view" is not effectively usable underwater without the same type of shutter delay you get on a PnS. Ditto the e510. So an optical viewfinder is still highly necessary in either case.
Cheapest I've seen the PT-E03 is about $690, sans port as with pretty much all other dSLR housings, and sans handles/tray unlike many others. At $1100 for the e-330 housing (by comparison) with at least a flat port and the handle/tray assembly built in, the Fantasea is still effectively about the same price. Ike is certainly higher at $1300ish for the e-330 but that's with handles and TTL included, so it all balances.
Not knocking Oly's offering at all: but it's more on par with the market than hugely cheaper.