Hello everyone,
I'm a newcomer to both diving and underwater videography. I'm looking for a not-so-expensive (less than 1800 USD?) setup that will still give me some nice quality videos. I'm thinking maybe a used Sony HC3 with an Equinox or Ikelite housing? Or would it be better not to spring for the HC3 and get a lower-end miniDV camera and a better housing?
Advice or suggestions would be appreciated!

For +/- $1800 you can actually do a little better.
B&H has a couple of package deals currently:
$1459 for the Sony HDR-HC5 in a Equinox Pro6 housing.
$1675 for the Canon HV20 in a Equinox Pro6 housing.
$1930 for the Canon HV20 in an Ikelite housing.
$1999 for the Sony HDR-HC7 in an Equinox Pro6 housing.
All of the housings are camera specific though.
Another option is to put either Sony in a TopDawg II. Which is a "universal" electronic housing option - works with all Sony cameras with a LANC port.
It sells for $899. B&H sells the Sony HDR-HC5 for $795 currently.
Limiting factor is that you won't be able to see the LCD screen in the TopDawg. A poster on another board said that the viewfinder is a little hard to see in the TopDawg also.
And the HC7 might have some low-light issues if used without lights. Read the comments at the bottom of the review at camcorderinfo.com for more details.