Well, I got those suypplies at Canadian Tire - a hardware store that sells absolutely everything except food. Up here in Canada, we (men) need two basic things to survive, Canadian Tire and Tim Horton's.
Reason I bought it all there is that the price is probably 1/10 of pool store prices - but I do know that Wally world has the hose real cheap too.
The barbed connector and clamps are probably attainable at any hardware store.

I am serious about using the rainwater from my garage roof (about 2000 sq ft) to fill my pool, for every inch of rain, I can get 4 inches in the pool.
The way I connect it is:
I have 2 rainbarrels that collect teh roof water, rainbarrel 1 overflows to rainbarrel 2, rainbarrel 2 normally overflows out of and identical hose as the pool drain hose to the lawn, I just disconnect that, fasten the pool hose and run it 100 feet across the lawn, fasten a barbed connector on the end to which I tie a bleach container filled with rocks and toss that into the pool, the top of the rainbarrels is about 4 feet higher than the top of the pool, so gravity does it's thing. I don't have any trees nearby, so teh water from my roof is very clean, also, having the two rainbarrels settles out any bird droppings etc that may wash down in the beggining stages of rain.