I have not played actively in about 6 months but came back recently and improved a few stones it seems. I am going to spend $50 on go books to help me reach my goal of 7D kgs (non blitz ranked games.)

I have read:
-elementary go series attack and defense (kinda skimmed at 6k)
6.5/10
-elementary go series tesuji (read important chapters)
7.5/10
-lessons in the fundamentals of go (read it all several times)
10/10
- lee changing tesuji set (do problems when I feel like it)
8/10
-collected games of shusaku (studied like 50-75 games)
8.5/10
-improve your intuition series (read the 2 I have several times)
10/10
-invincible (haven't started, will soon)



I think my fundamentals are pretty good from reading lessons in the fundamentals (still can improve some more), my reading is ok, but my opening is pretty weak as pros are using joseki I haven't seen nowadays, I'm like 5-10 years behind.

I'm thinking about getting a pro game commentary book and an opening book, but not sure what would be good for my level.

My suggestions

Pro Game commentary - Lee Sedol's Commented Games vol 1

Opening assistance - SmartGo + GoGod database.

This is a lot more than $50 though.

Like this, you acquire no(t enough) skill:) With luck, $50 suffices to become 3d: Rin Kaiho Fuseki Dictionary (buy the cheapest edition available somewhere in the world). I assume that you have a game collection and need not spend money for it: study 1500 games up to ca. move 170, study Go Seigen from 1933 on, a few Shusai games, and solve as many LD problems as you can. (It is pretty much what I did to become 3d quickly.)

If you were willing to become stronger by spending more money, I'd suggest a couple of further books. But since you don't...;)

Not interested in gogod.

Will look at those two books :p.

But my theory is improving isn't about say learning this or that, but continuing to build on my fundamentals, so once in playing proper moves I basically need to learn my play style and how to play the moves where there is no outstanding obvious move. Basically l&d to me is not worth anything, even though people advise it so much I see no benefit of l&d for the most part.

I'll check reviews of the seedol book

I can vouch for this book. It has the best reviews I've ever seen, although that's because there's only 3 games in the entire book. I recall each game taking ~100 pages to review fully.

IMO, it is the worst pro game commentary I have ever seen: I learn nothing from it. But maybe it is not written for my level:)

Very good! This is what you will need from 3d to 5d. Very easy things only, but each small fundamental is very important. Since finding them by yourself can be very time-consuming (I needed years), you can read a good percentage of those fundamentals in Joseki 1 Fundamentals and Fighting Fundamentals (get the PDFs to save money). Because you have the right attitude of acquiring the fundamentals, you can appreciate them appropriately. Much will seem easy, but do not underestimate the easy. Rather take each piece of taught information (such as a principle) very seriously. IMX, the easy (but initially well hidden) things are an important factor for improvement. If I knew more such books, I would tell you (ok, maybe Fundamental Principles). Some 50% of the fundamentals you still need to discover by yourself.

Right now I'm really interested in haengma I think it was spelled? I don't really care if it is anything mysterious as people seem to say, but from reading about it I am already feeling I am learning something, thinking in a more fluid way than being tied down in my usual thought process. Maybe it's just something I had forgotten, and its possible its not even haengma, but something I've realized that is different.

Anyway I don't want gogod, probably not the seedol book. After thinking I might want a haengma book, some other book like invincible, or some other book that can teach me how to think, not just how to respond.

Although you can read every book on haengma and every book on other strategic concepts as well as books on judgement or how to think, and although I would recommend to read all the hundreds of books somehow related to those fundamentals, there are, for the intended rank range, no such particularly noteworthy books that you really would need to consider given your tightly limited money to be spent. Haengma amounts to efficiency and stones working together meaningfully; a pile of books will not tell you (at your level) that much more. How to think? The by far most important hint is: reduce your blunder rate. You do not need a book for that, but control your psychology.

I have been thinking pretty much that, but I also feel like I could use some more insight into pro thinking, or something earth shattering that I did not know before. I understand.. Say 90% of pro moves after I see them, but can only predict say 20-50% depending. The moves I know the best are usually the big starting move of the midgame, but often but the moves I hardly ever predict are tewari kind of moves, or special sequences. Basically the meat of their game or play style outside of the proper moves that you can expect. That is why I think commentary over those parts would help a lot.

Unfortunately, good literature on advanced techniques is sparse. Anyway, firmly understand the fundamentals before going too much into advanced details. Thereby, you will see that a lot of what initially seems advanced really is basic.