I think most of us can appreciate the desire to keep a blacktip, but... you need to do it right if you're going to try. A 300 gallon tank isn't going to work. In the mean time, go with a smaller species, save your money, and be patient.
There are a lot of shark veterans here (including myself). I think it's safe to say that the majority of us want to see new shark keepers be successful. However, we do want folks to do their homework, have the proper equipment, and consider what's best for the animal.
Good luck!
mattiej:
What is your current inventory looking like?