Sometimes the price for a gimmick or method seems outlandish, but it is usually a fair price. A lot of time went into creating and perfecting the contraptions and performances. Not everything out there is just trying to get you to buy it. Trailers can be misleading to an extent, but a lot of what is released is expanding knowledge of the art and getting different effects into more hands.
Every routine has been done, many times and in many ways. You are not going to come across a brand new effect that isn't at least inspired by something that has been done for the last 50-100 years. Torn-and-Restored will continue to be re-invented with new methods, so why pay $20+ for one?
There are a few reasons to buy a product. First off, we all want to know the secret, like, that's why we are here. Secondly, we are adding to our arsenal/repertoire (lol, our "bag-of-tricks".) Thirdly, maybe we just want to support the creator/producer. We have reasons to buy these products, and now to justify the price.
Will you ever use this? That is the key question. If you will use this, or think you may use it in the future, get it. It doesn't matter if it is a $9 download or a $200 invisible thread gimmick. If you can afford it, buy it. If you can't, don't.