I've just ended my latest run with
Life: 14356
Attack: 2058
Defense: 2264
Gold: 88
Experience 33
This is before I bothered Chaos.
I also only bought health once.
My advice is to buy attack with gold and defense with experience for most of the game with only a few exceptions. For example, you might buy defense with gold once before you reach the old man that trades experience for stats and bringing either stat up to both shrug off the attacks of the bosses and do damage to them.
You may also find it necessary to save a little money to buy a few red or blue keys during the climb but there are a few doors that don't need to be opened so you will likely end up with more keys than you need at the end.
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