Wether the feats are worth taking kinda depends on how much downtime you are excepted to have. If you’ve got a lot of downtime (and a decent supply of spare gold, either through adventuring and/or the ´Earn an Income’ activity, by yourself and team members) then the feats can be pretty good. More so if you know what may be coming up when your group decides to go on there next adventure (as you can start tailoring your crafting towards the needs of that adventure.) It basically becomes a way to better fit/supply your group with less gold spent, in exchange for time. Also, it can be helpful if the items on sale are limited (for example, higher level items may be more difficult to obtain from the market, but as long as you have the formula, there is nothing stopping you from making it.)
If however you find you do not have a lot of downtime, then these feats become fairly weak to mostly useless. In order for you to both craft items, and at prices cheaper then market, it takes time, and without it, your not making/getting any value from these feats. The other (less common) problem is if you have downtime but not access to materials (ie you have downtime, but it’s on a ship that does not posses the materials you need, for example) There is also the possible problem of the difficulty of obtaining formulas (which can be solved with the Inventor feat later on, but that does mean more time is needed, and further feat investment to solve.)
Ultimately, wether these types of feats are the most powerful feats in the game, or a waste of space, is going to be dependant on the campaign setting and theme, and most importantly the DM.
