Nope, 1/4 is the only 28 thread I have. Napa or AIH will have them but it will be about $30 or so. Palmer Machine would do it for like $10, he taped 3 holes I drilled the minors in for 1”npt for for $10 back about Christmas time.
1/2-13 and 1/2-20 are the standard tread counts. I don't think you will find 1/2-28 locally. MSC has them for about $16 for the low end ones. Enco also has them for $11 for an import.