There are a lot of good comments in this thread already, but I would like to add that having a good bench psu is very important. It has to have current limiting, if it doesn't you might as well use an atx PSU on the bench. It is also good to have more than one output(double, triple) . This way you can power stuff like an old cdrom drive with a current limit on both 12v and 5v.
Rgarding fume extraction. If you can get fume extraction that is great, but if you can't... Let's say it never stopped me from soldering ocassionally, but I have a window right next to my workbench so a lack of ventilation is not a problem.
People mention a microscope in a context of smd soldering. I woukd like to add I use my microscope for a lot more stuff. I use it (on 10x) when soldering tiny connector elements, even a lot of through hole stuff like Ic sockets etc. Is it necessary? No, but it is really nice to really see the soldering process.
Regarding microscope type I would skip all the stuff that uses any kind of screen. I use a stereo microscope like this
https://deltaoptical.pl/mikroskop-stereoskopo … cal-discovery-l
At the time it was the most expensive thing in my workshop, but it is well worth it. I can't imagine using anything else and it made soldering and analysing Circuits much more enjoyable.
Also, I would like to comment on the initial idea of saving money by buying broken stuff and repairing it. In my opinion this makes sense only if you can get the damaged hardware for dirt cheap and you have a couple of the same type. Even better if you have a source you can trust. For example, many years ago I used to work in a PC repair shop. We would just replace customers broken hardware, but we had "a guy" that did board level repair too. Every now and then he would come over and buy a whole box of broken GPUs, motherboards etc for the price of scrap.
Buying anything sold as broken online is much more of a gamble than buying "untested". I found stuff sold as untested (typically - "pulled from a working computer 20 years ago, sat in a garden shed since") is a much better bet.
Sure you may come across stuff with broken voltage regulators, lifted traces, puffed caps, and other fairly simple repairs sold as broken, but there may also be stuff with broken vram, main chips dead etc. These days "normal people" are aware of retro enthusiasts and that some stuff is valuable. If someone has something expensive, whether a geforce 3060, or some of the vodoo cards that's dead or damaged do you think that person would just list it for $20 online as broken without attempting a repair? IMO a lot of expensive stuff sold for cheap as "broken" has already went through at least one round of attempted repairs. Then when fixing you have to worry not just about the stuff that usually breaks, but anything else the previous "repair person" messed up.
Then there is also the cost of your time and general availability of exact same type of cards.
That's why I tend to stay away from such stuff.