What state/city are you located? I received my IV blood withdrawal certification from a class given at kaiser hospital in hollywood. Great instructor and after completing the class you're allowed to return as many times as you want without repaying the fee
One of my teachers told us about the NFLPN (National Federation of Licensed Practical Nurses) and they have an IV therapy certification so you may want to check that out. I haven't done it yet but just might!
I took my IV cert class when it was offered by a pharmacy group that catered to SNF where I lived. It was 2 weekends in a row, got my successful sticks while in the classes and received my cert right away. I googled IV certification then got more specific with my location at the time. Check it out and good luck!