The only thing I buy from my center is the EFA - it's $21 a bottle I think, and I like their formula because it doesn't have any fishy burps along w/it - some EFAs do that and I can't stand it. But you can totally find that at a vitamin shop (probably for cheaper) - I just haven't had a chance to look yet.
I generally buy all my HSNs from
www.dietdirect.com - I wait for the Proti Diet Concentrates or the Bariwise Powders to go on sale, and then I stock up and by 15+ or more boxes - if you buy like that, you can get them down to like $8/box w/free shipping included. I only buy HSNs from my center when I am out of Proti/Bariwise and DietDirect isn't running a sale - then it's the same to just to pick up 10 boxes from my center for $90 (and wait for the next sale online). The key is to ensure that whatever formula you decide to purchase, ensure that you're getting something with 15 g of protein and less than 4 grams of carbs per serving.
All my other vitamins and whatnot, I've gotten from my local vitamen shop. I used an online version of MRC6 for six weeks (called KLB5 and purchased it from bariatricfoods.com, I believe) - but decided to stop taking that all together to save money about 3 weeks ago and have had no noticiable ill effects from stopping that (i.e. it did not slow down my weight loss or my inch loss).
The centers don't sell bad products - they just tend to sell unnecessary products or overpriced products.
Best of luck to you!!