hi Matty
go to links on the left of this page and click the Bintel one.
Sellect
"ccd imaging and accesories"
on page 3 you'll see
"Orion Camera Adapter Prime Focus 2"
I rang Bintel this morning and spoke with Don who told me the Bintel brand one is exactly the same, out of the same factory but much cheaper.
The Canon T-ring is on the same page but you have to specify
EOS
As for the cable release, I am not sure as I know the 40D one is different from the 350D and even the 30D, I have no idea what one the 450D will use. I notice they are cheap enough on Ebay though.
I hope this helps and anyone else reading this, if there is anything else we need please chime in.. I'm in the same boat as Matty