Would i be possible? I was thinking of just DIY 75 gallon. I don't know how much it would cost so is it doable and would it be substantially cheaper than just buying it to make it worth it?
you would be better off just buying it man. Evben new they dont cost much. Ofter you will get them free on Craigs List. Unless you have experiance sealing the glass etc, I dont recommend it. The last thing you need is the seam of your tank busting open
def. not worth it unless you have experience building tanks, and by virtue of the fact that you asked the question I am going to assume you don't. you would save very little money anyway, since as herman mentioned you can get a 75 very cheap, free even, yet you expose yourself to total loss due to tank failure.