I'm in the deep end of the pool on this, technically speaking, but there could be variations in how the web page is delivered from the bank, which could influence how much info you get when you do save.

For instance, some data base systems now serve up info and interact with you through something like Flash. How that might translate to an HTML save is unknown to me. But it would make me nervous.

I would lean, myself, towards generating a PDF. Set your default to smallest possible file size to minimize the amount of hard drive needed to store it. You won't really lose quality in terms of your purpose, since you're mainly interested in the numbers. Graphics will look fine for your purposes, since you're mainly viewing them on a screen or printing them out with a home/office printer. You don't need National Geographic quality.

Wish I were disciplined enough to do things like this.