Tank/piranha Questions

Hello, I am thinking about getting a piranha, or piranhas. I was wanting a recommendation on which type I should get. I have a tank that is ATLEAST 100 gallons, I know it is 6feet long, if I remember correctly, it is around 16 inches wide. If you recommend a piranha species to me, please provide basic information if you can. Another question I have is, if I get a shoal of red belly piranhas, what should I do if they have eggs? I don't know where I could sell them at. I do have a 55 gallon tank for the fry, but I would not know what to do with the babies. If you tell me a good place to get sell them to, how long would the 55 gallon tank last for the piranha fry, before it is too small? Please do not recommend something to me that is a lot of money, I plan to spend at most 100 dollars worth on the fish, Which means if I get something like red belly piranhas, I would get them as juveniles. I have done some basic research, but I would like to ask the experienced themselves. If you feel like there is anything else I should know, please tell me.