Thanks for putting so much work into this. It took me all week to get through it, which was great. I had stuff to listen to on all my drives to work.
Even if you end up wrong on each card (highly unlikely) just discussing them is important.
The MTGO wiki price is a new thing that I discovered from my pal @Islandswamp
Some cards can be hard to find from general chain bots. Like For example, Nemesis Tangle Wire is $50 but the promo Tangle Wire is only $10. Because of that price difference, the promo Tangle Wires are hard to find. MTGO wiki prices tells you exactly who has them for the cheapest price.
I'll also add that once you purchase a card, it can be difficult to get the exact value back that you paid for it. I would expect to only get 80% value back each time you make a transaction. For example, I have a tendency to try really "out there" decks, so I might spend $50 on a set of Stifles and then come to the realization that Stifle is a terrible card. So I'll try to sell the Stifles for something else I want to try. I'll probably only get $40 back for the Stifles and so then I buy a set of Goblin Welders for $40. If I decide that Goblin Welder is terrible, I'll probably only get about $32 back for them. Just something to be aware of.
I think that there is a bug in the site whereby if a post is deleted it doesn't detract from the total number of posts in the thread. It's also possible that there is another unrelated but that is causing the number of posts as counted and the number of actual posts to be in disagreement such that one is incorrect. The net result is that going to the last post in the thread either by using the end key or by clicking the pop-up that takes you to the last post in the thread instead takes users to a blank page.
If I manually enter the post number I want to skip to in the url I can find the actual last post based on the last post number minus one but it still not the correct number for the last post since the post count in the thread is apparently wrong. If I dial the post number back far enough in the url (by about 4) it will eventually catch it and dial it back to the actual last non-deleted post number which appears to be the post count minus the number of deleted posts minus half that number again.