You are welcome to go through Sears PartsDirect for parts, or you can call Whirlpool regarding your dishwasher. The prices should be comparable.
While your situations are certainly frustrating, a few things ought to be kept in mind:
1: Nobody said dishwasher racks were cheap. They aren't, at around $100-$150 a piece. By way of comparison, a walk-behind lawnmower engine costs $300 by itself (as much as a new lawnmower). Parts cost a lot because they're essentially dead inventory. They're merchandise that usually won't get sold for quite a long time (sometimes years), and the company has to store it, which costs money. The larger/heavier a part is, the more it's going to cost. When you purchase a fully built product, the cost of the parts to make it are lower because that product is definitely going to be sold, and thus all the expense of maintaining inventory is not incurred. This is how the parts business has always been, and it's not likely to change until storage space becomes free.
2: Call any dishwasher manufacturer, or use their website, and check the prices of their racks. I think you'll find them comparably priced, for the reasons mentioned above.
3: Bacterial growth happens in EVERY dishwasher, regardless of brand. There is always some place that is not exposed directly to the jets, and will retain moisture. There is no dishwasher sold in any country by any manufacturer in which this does not happen. A dishwasher is not a magical machine. It uses water, and any appliance that uses water has the potential for bacterial growth. As such, it must be treated and maintained properly, including periodic cleanings (if you think having to clean something that cleans is silly, consider not cleaning your shower for as long as you haven't cleaned your dishwasher and let us know how it turns out).
4: To avoid rusting racks, select a dishwasher that has nylon racks. Nylon is far tougher than PVC, which is what cheaper dishwasher racks are coated with. Not knowing personally how old the Kenmore Elite dishwasher is that the original poster has, I can't say for sure if it has nylon racks or not, but almost the entire current Kenmore line-up, as well as most Whirlpool, Maytag, KitchenAid, Jenn-Air, Bosch, Frigidaire, LG, Samsung, Electrolux, and GE dishwashers have nylon-coated racks. It is becoming the industry standard.
5: Sears sells the exact same products everybody else does. Best Buy, Home Depot, Lowe's, Sears, HH Gregg, and the independents all sell basically the exact same products (though there are a few store-exclusive products here and there) and at similar prices. So, if Sears sells overpriced junk, then so does every single other retailer in America, and you are therefore going to buy overpriced junk one way or the other. Unless, of course, you're going to get a Miele or Asko or Smeg, brands Sears and most other retailers do not carry.
5: Sears is not a manufacturer, any more than any other retailer is a manufacturer. Sears is a retailer. Sears sells merchandise, it does not make merchandise.
So, if Sears has the same products as everyone else, and if every other manufacturer charges about the same for a given part, and if Sears is just as unable to change the laws of physics and biology regarding water distribution and bacteria in dishwashers, how is Sears singled out as the bad guy?
I'm not saying frustration isn't justified, or that people can't say what you want (within reason), but it doesn't appear that what's being said is based on facts rather than frustration.