Bump on Red Ear Slider turtle's neck?

I have a Red Eared Slider turtle and recently it just got a bump on its neck. I was finding solutions to this problem and there were two answers-- 1 was to take it to the vet, or 2 was to use Betadine Solution/providone iodine. Does the Betadine solution really work, and if a vet is needed, how much would it cost to get it removed? I am not saying that I am going to abandon my pet if it is too expensive, I just want to know beforehand.