yes there less expensive than most other sellers, but a 300+ gallon aquarium is not what you wan to cheap out on, i've read some horror stories about GC tanks, not as many as others, but i'd go high quality like tenecor.
I have tried to deal with that guy for a big tank (600gal), i asked him the cost of the tank i needed w/ aprox shipping costs, he replied. I emailed him again asking him how much the cost of some other sizes of aquariums were because i was trying to figure out what the cheapest cost to me would be. He sent me a really nasty and angry reply back that didn't make sense. He said he doesn't do business that way and he doesn't deal like that. I emailed him back wondering what he meant and never got a reply back. I just got a local tank maker to make me a aquarium.