@truepurple It's explained that she can't get the tools on her own. She's going to need some really good connections. In chapter 18, the Guildmaster already showed interest in her ideas and having her work for them.
It's chapter 20 that she was told that the consuming could be cured with lots of money.
In chapter 24.5 Benno said he didn't have enough connections.
Chapter 25 is where they first used a tool and were pretty much going pay for it now or you have to work for us. Also that even the guildmaster was only able to buy tools that were already on the verge of breaking and that it cost much more for a good one. This is where the slave part comes in, since she'd have a contract to work for the noble to get the tools.
Edit: About the time thing, in ch 25 they also state that it will need another in half to a full year of time and that they get more expensive.
Note that Frieda in ch25 states she already has a contract to marry into a noble family in exchange for the tools. If the guildmaster could make enough money I highly doubt he would have allowed that.
As for the last question, you'll see the answer to that in some of the spoilers. It's largely a conspiracy for various reasons.