[MATTBIN]

AP Valves do the cam bands, your local shop should be able to get them, or ebay sometimes (£15/20 on ebay I think). I've used them (as Bryan/Finless says) they were fine if a slight faff between dives if you swap to a second cylinder. Currently I dive twins indies on cam bands. Dont bother with a button pressure gauge, if you want a gauge make sure you can read it during the dive. I used to dive mine with the valve down, gas it up before I hit the water and turn it off as I went in, just in case it leaked during the dive.
Weighting - ensure you weight yourself with an empty main cylinder (leave a little in during the test though - just in case) and a near empty pony so you can hold a 6m stop if you have to, get a buddy to help doing this. You will be in taht situation if the crap hits the fan, its no good weighting yourself with 50 in the main cylinder (unless you compensate of course).

HTH

Local farm should be able to supply the hay, the pony droppings are good for your roses.

Matt