Get someone to chip in with you.
Or if you buy it, it will probably just sit on your shelf, for the occassional shot every now and again. It is an aquired taste, and don't give any to young girls as I mentioned earlier in this thread, unless vomiting is required.
I am not sure of the difference sorry, I have only had the green one.
But for getting fucked up, if you had 5 shots, I'd say you would be on your way. I'd say try an over-priced shot from the bar with your mates, then decide on whether to get one or not.