Todd: Well, we've still got 600 gallons of methylamine.
In Season 1 Episode 7 “A No-Rough-Stuff-Type Deal”, to get around sales restrictions on pseudoephedrine, Walt and Jesse start using methylamine to cook their meth (a process which results in the blue color of their product). They eventually, with the help of Todd, steal a lot more methylamine during a train heist (Season 5 Episode 5 “Dead Freight”) and this is the methylamine Todd is referring to here. Lots of methylamine = lots of meth = lots of money. Or lots more money considering all the money Todd and his friends have already stolen from Walt.
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