Unless someone person is linked into a larger case, drug trafficking, human trafficking/gang related, racketeering, no one selling under 50-100 packs(outta state) is going to have their phone tapped.
A Title III wiretap is the most invasive, and it signed off my a federal judge most times, needs to be supported by a warrant, it costs about 60k, I think, and has to renewed every month or so, to reevaluate. You see this in serious drug trafficking/gang cases, not guys doing "direct sales" with weed
Wire taps in most cases aren't fishing for info, they are confirming what they already know, for evidence in a conspiracy charge, and looking for new leads.