Tanks on line is very, very doubtful wrt to saving $'s.
IMHO your best bet is a good used tank.
My experience is that local vendors (such as Walmart and PetCo) typically offer only very, very low end products such as filters and if a LFS offers a high end product the cost is significantly more that the on-line purchase cost.
I have had good luck with
and can recommend them.
Their on-line help can "walk you through their web site" and also go to their storage in order area check on the availability of items which are not published.