Everything in this tree is super expensive for non whales due to the way this tree scales. The tree start off with everything at 2x+ the normal price, and gradually drop down in prices as you spend more on it. If you drop 30k+ coupon/ingots on it, you can get quite a good deal. For everyone else, it's pretty much a claim your free stuff and ignore event.

A lot more than that. It takes about 200$ to reach the point of having future investment not being inflated in price. It takes about another 100$ after this point to make up for the inflated prices for your first 200$. So unless you are planning to spend over 300$ (or coupon equivalent) on the tree, you are actually purchasing things at more than the typical non-discount prices.

Now, if you go crazy and spent 800$ on the tree, you are buying stuff at around 40% discount on average, which is a really good deal.

This event is all or nothing, basically.