When it comes to turbo kits, especially singles with fabricated mounts - I'm sure the vendor gets quantity pricing on the parts they don't fab - the turbo, wastegate, etc. Those I can understand not having 10 or 20 in stock - that's a LOT of inventory to sit on. However, in the case of the manifolds, there appears to be too many vendors doing a group buy for "vaporware" they may have a jig, but no manifolds already in stock, no flanges, no tubing, nothing. The fabricated parts should be on hand and ideally already welded and awaiting orders. Is it costly? Yes - it is a risk to build 10 or 20 manifolds not knowing if they will sell? Sure, but business is risky. It appears to me that most of these "shops" are just fabricators that want a lot of work to stay busy. What's really funny is - all these vendors would need to do is set them up as a Kickstarter - then they could take 3 years, not make shit, and no one would care!
I look to MMP's group buy as one of success. I doubt Mauricio expected the number he got in the first batch - I'd guess it was probably double his expectation. He had the first 10 sets done immediately or very fast if I recall. He set the timelines for the rest based on what he had in stock manifold wise, and the lead times for receiving parts, and different taks, i.e. coatings. When he had a delay from a supplier, he immediately told everyone. I can understand the nature of wanting an update every day, especially if you've paid a good amount of money for something, but I never felt dismissed while waiting. When he said he had everything and would be shipping stuff out, I figured he would be assembling all the kits, confirming the parts then shipping them all - assembly line. Some people were asking "why didn't you ship mine today if you had the stuff, I was first on the list." Doing 15 different tasks to ship one package is a recipe for disaster when it comes to bulk orders. It's much more accurate to do a single task to every order, then the next task, etc. It might take an extra day before order 1 is shipped, but the next day 30 orders are ready and they all are correct.