I would avoid 9mm. The popularity of this caliber has made ammo expensive or hard to find around here. I heard a guy ask about 9mm ammo at the gun show today and the guy selling ammo suggested the buyer buy a different gun to get through the current 9mm shortage.
I did see 9mm ammo, $38 for 50. I also saw 9mm cases $48 for 500. I thought both to be too high to sell.