I live in Kansas 3rd and I'm here to tell you that I've not heard of a single GOP challenger for Moore in this election. His last opponent, Kris Kobach, lost by 11 and a half points in 2004, such a horrendous margin that he can't be considered a serious challenger anymore. The moderate Republican from 2002, Adam Taff, just got sent to jail for 15 months for messing with his campaign money. Nobody is stepping up yet, nobody has been seriously mentioned, and with Moore's campaign chest time is running short. Look for Kansas Third to remain solidly in the Democrat camp.
Indeed, it remains a problem that in KS-3, there are effectively 3 parties, the Democrats, the regular Republicans, and the "Moderate" (liberal) Republicans. Until you can find a candidate who can appeal to both wings of the GOP (good luck there), Moore continues to benefit. You are correct Moore has raised a fortune.
Congressman Dennis Moore is being challenged by state Representative Scott Schwab and banker Chuck Ahner.