It is an absolute obligation to check suits for shaatnez when many such items have it. It’s no different than checking for bugs in lettuce. It’s not “questionable.” You’re not allowed to wear shaatnez and you can’t assume that something doesn’t have it when you know that many do, even a miut, because we don’t go after the rov/majority when it’s efshar levrurei, possible to clarify. What that has to do with money is irrelevant; if you can spend money on a suit, spend 8 dollars to get it checked. Some checkers do it for free if they know a person is strapped for cash. The shaatnez community is one of the most ehrlich segments of klal yisroel, in my many dealings with checkers.
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