Sounds like a good selection to me. I have a pineapple express freebie going myself. I almost couldn't resist. I'm not familiar with purple chem, but LA Con and PE both have good reviews on
Seed Finder and I've heard good things about them here too. You're going to want to get started right away for maximum yield. It is starting to get a little late in the season. Still definitely worth the effort though.
I really dislike MG soil. I've actually used the potting mix in a pinch without much ill effect, but I had some serious issues with the moisture control stuff this year. After planning my 2012 grow for months, I made the stupid mistake of taking all my pro-mix out to my patch. When I realized I didn't have a bag to germinate seeds in, had to run to wal mart and pick up a bag of MG moisture control since where I get the pro-mix doesn't keep it in stock I have to special order it. Big mistake. Way to heavy of a soil to be germinating seeds IMO. Seeds survived a and bounced back once I transplanted them, but I've been starting seedlings this way for almost 3 years and never had a set have such a bad start as the round in the MG soil. Peat-based mixes like pro-mix and sunshine mix are the way to go. Hell, I think I would have been beter off just using straight peat moss.