I don't have Kaplan's QBank, but if you go on their web site it says that it's $199, not $499. I've been trying to decide if I should buy it. From what I've read, the QBank questions are considered harder than real MCAT passages, but some people say that's good practice for when you get a really freaky MCAT passage on the real thing.
There's also a book by TPR called Hyperlearning Science Workbook that has passages (I really like this book - very good explanations), and they're all indexed by specific topic within each subject. There's around 60-80 passages each for physics, biology and chemistry (as well as a bunch of discretes), and I think about 40 passages for organic. You'll just have to look to buy it used from someone who took TPR's course. I'd check SDN's for sale forum, as well as ebay and craigslist in your area.
Examkrackers also has a passage-based biology book (part of their 1001 series) that you can buy on Amazon. The other 1001 books are good practice by topic, but not passage-based. Good luck!