I applaud your gusto to do it yourself -- I'm that kind of guy too. But in the case of a complete upholstery job I would think long and hard about trying to do it all from scratch, especially if you don't have experience in this field.
There's a reason upholstery jobs are expensive -- it's very time intensive and the supplies are not cheap. I know of what I speak!
Five or so years ago I completely redid the upholstery on my TriStar. I found a good person in town who worked at an upholstery shop during the day and then did custom work at home in the evenings. She agreed to do my stuff for a good price as long as I supplied all the materials. I pulled all the skins off, and once the new ones were made, I reinstalled them myself.
I used SurfSide marine vinyl which runs about $33/yd. Then there is thin foam underlay that is needed for some of the sections. Then there is special thread. Then there is the welting which has to be made to match. Then there is the Hidem strip material -- which either has to be made or, if you are lucky, can be purchased to match. Then there is the tack-down material to secure upholstery sections to the base between the seat foam sections. Then there is plastic to cover the foam so that the skins slide on nice and easy. Then there are stainless steel staples -- I likely spent $100 on staples alone! And on it goes.
So when you add up all the supplies, and considering that time -- your time! -- is money, the amount that a professional upholsterer charges doesn't look so bad. And at $33/yd, learning how to sew vinyl can be an expensive lesson.
Im not saying you couldn't, or shouldn't do this. I'm just saying . . . carefully count the cost before embarking on a task like this.
(Just yesterday and today, I stripped the skins off the two bow seats and rear seat of my X5 which I'm planning to sell next spring. I'll be taking them to a local upholsterer who has agreed to do all three for $440. If you shop around you should be able to get most of your skins redone for somewhere in the $2000 range.)