chic...
A lot will depend on your foundation requirements and your selection of coatings.
Without any other information, I would guess about $2.50 - $3.75 per gallon for a bare tank.
Add about $18.00/sq ft for coatings (inside and out).
Add to this cost of foundation, platforms, secondary containments...etc.
Please come back to the forum, Steve ....with your figures !!!
Go Steelers !!!
-MJC