If you are going to try Parelli, I would urge you to buy the Level 1 pack. Trying to do it from directions of a video clip with NOT help you. Then you run the risk of saying "I tried Parelli and it didn't work." Plus those won't give you the Why's......as in why you are doing what you are doing.
Not all rope halters are created equal. You can buy a cheap one, but really it will be a piece of poo. Cheap ones, unless made from the exact stuff Parelli makes theirs from, will not have the feel that the Parelli ones do. Same goes for the lead ropes.
It may seem expensive, but when you get right down to it it costs no more than sending a horse to a trainer, buying more equipment, taking lessons, etc. The amount of information you get in the packs is huge. It's worth the investment.