Don't rag on this guy too much, We have all been there. Starting a tank before we even knew what the heck we were doing. I am still a noobie to this, but having started a freshwater tank with fish that would outgrow my tank, I can understand where he is coming from. Because of not doing research and just going with whatever cool fish I seen, I ended up killing two of the fish I really liked. I planned on upgrading as fast as I could as soon as I found out the problem, but because of my lack of knowledge and me moving around a bunch of stuff in my tank, I stressed an easily stressed fish and they got ICK and died. So lesson learned. That is why I am on the message boards here learning as much as I can about my fish I want before I restart my tank to a saltwater tank.
A lot of websites say that Lionfish would be ok in a 75 gallon tank, so I can see where he is getting his information. I agree with a lot of people that you should listen to more experienced people, that is why I am here. My only advice I would give is to get a tank off Craigslist. I have seen many deals in my area for 125 gallon tanks with tanks and stands for as little as 500 dollars. Before buying make sure you check it out!! I am sure there is threads already on this website that can help you determine if a used tank is a good deal or not.