Gopro is pretty good underwater for the price flat housing is needed like many have said there are many options available, the fixes that do fit inside the normal lens are ok but are really only useable in 1080P due to the vignetting + you have to replace the lens yourself and risk flooding your housing if you muck up the install. I have one of these but as I prefer to shoot in 720P underwater I don't really use it much, quality in 1080P though is good but footage gets very shakey easily in that mode so unless its kept very still footage is fairly useless. These are made by a few companies im not sure of the pricing I think around the $20-50 depending on which one you get, from what ive seen though there is not much difference between them. If you add it to your only housing then it will limit shooting to 1080P even out of the water so its best to get a second housing aswell if going that way.
Eyeofmine housing is good as can be used in all modes except R4 with no vignetting and it comes as a complete housing package, main negatives are the fact that it is a plastic lens and can scratch up fairly easily and trying to clean the inside lens is not easy due to the design as it has a fairly large section that's kind of undercut and if you get a little something in there like I have its a real pain to get it out. I have one EOM single housing and also just recently got their 3D housing which I film all my UW videos with atm. Pricing for them is standard model $79 rated to 30m 100 feet, $99 Professional model pressure tested to 200 feet 61m for 1 hour, 3D professional housing is $149 they all come as a full housing package.
If you check on the forum here there are some posts from blurryfix about their new flat lens they are about to release, vignetting will be equal to or better then the eyeofmine, it uses a high quality glass lens which is interchangeable with different coloured filters to give better colours under water. They said the first versions will be as an add on for existing housings but unlike the eyeofmine it retains the original gopro lens on the housing so no risk of flooding your housing even with a bolt on mod, I think eventually they will make some as a complete housing packages. I will get one of theirs when it comes out and will make a comparison video for the 3 main solutions to give people an idea of which way to go. Pricing is $69 dollars for this and it goes over your existing housing but can still be used in all modes vignette free other then slight r4 and photo you could add UV and polarized filters for improved images on land with it.
Ive been asking gopro for ages when they will release the underwater housing and keep getting the same answer you got, I think the blurryfix idea will probably still be a better solution though simply due to the ability to add screw in lens filters so it sounds promising. Unlike the EOM if you do happen to scratch the lens it will be easily changed without having to bin the complete housing.
