my dad only allows us to buy the family the most generic, disgusting food brands. but he just bought a 50000 dollar porsche. theres always someone with a worse dad...
OK... now let's be fair to the dads of the world.
That they don't spend as much money on you as you'd like is not a reason to call them bad fathers... some might be- but a father's quality is not judged by how much he spends on his children.
Until you become a parent you won't really realise how much money IS spent on you even if you think otherwise. You may think you do- but you really don't.
My wife came from a better off family than my own- and she actually wishes her parent's had spent less money and more time on her when she was a kid.
Money spent does not equal quality of parent.
(Oh, and generic foods are usually made by the same people as a name brand food in the same place)
Back to the original poster's topic- $100 is a great deal for that set-up - if the issue is that your father thinks the tank is over-priced he is incorrect. He may not realise how much they are...
...if he just doesn't want to spend that much- then that is his choice. It doesn't make him a bad father. It is just one extra expense on top of a mountain of other expenses.
Everyone wants their parents to be fiscally responsible and not dig themselves into a hole don't they?
Anyhow, good find and good luck. You can do great things with a 100 gallon aquarium.