I agree with Karin, the PT-E03 housing for the E-410 has been sold out at Olympus America for some time now and regardless of the listed price most dealers are also out of stock and will not be getting any more housings no matter what they are telling customers.
The PT-E03 is a great little housing for the price and the package produces excellent results.
I think it is short sighted of Olympus not to have a redesigned PT-E03 housing for the E-420. An E-510 housing would require a complete new design and the upside of Image stabilization would be limited in U/W photography. I. Q. will likely be the same between the two cameras. Not to provide a path for upgrade to those who have invested in ports, gears and other assorted equipment is wrong.
I can understand Olympus partnering with Nexus on the E-3 housing because it is a much more expensive camera/housing combo which is not Olympus forte, but to leave the E-420 to outside venders in hopes someone will build an inexpensive housing that excepts Oly ports is a gamble.
Phil Rudin