This could be a blessing in disguise. I've also used pure IP products for 2 months and then moved to alternatives and discovered a number of products that I like better. The variety is greater and the savings is amazing. My weight loss on alternatives is just as good as it was on IP branded products.
One other thought - at least from my perspective - is that in maintenance I will most likely use a few of these products to keep me happily in check. For example, I have a sweet tooth and that has been my downfall in maintaining weight. Plus I found through this protocol that a low carb regime really helps my body feel painfree from an arthritis perspective and I also have lost bloat (probably due to a no-gluten diet).
That said, in maintenance, I can have my cake and eat it too, so to speak (that's a crazy phrase, now that I think of it...). Using Nashua Nutrition's Healthsmart Variety pack, I can have what tastes like a candy bar every day. I love all 7 in the box, love the variety, and the price is around $11.00. Very reasonable price to pay to keep my weight where it needs to be.
So, if you didn't learn firsthand about alternatives, you wouldn't have this understanding of just how helpful they could be in maintenance, and importantly, how affordable - important for the very long term.
Re vitamins, I only buy the IP branded potassium from www.plainprotein.com since it is highly concentrated; any other brand would require taking so many pills. The other vitamins are easy to replace from most any source.