I found this review a few weeks ago, after I happened to examine a MINT condition "beercan" at my local camera specialist pawn shop...I had not seen one in many years, and this example was simply immaculate! And the price was like $129, or $119. Can't recall...I looked at a bunch of lenses that day.
Keep in mind that the A900 also costs $1000 more than, say, the 6D, despite having a significantly worse sensor across the board, far fewer features, much clunkier size, and generally more creaky old tech.
The image stabilization in-body might have something to do with the price still being so much. Similar for a more modern alpha 99.
So you may be paying $500 less for the lens that ends up working just as well (or occasionally better). But a lot of that cost is probably simply getting shunted over to a more complex and expensive IS-in-body design instead that costs $1000-2000 more than the abilities and features it delivers competitively.
Also note that with the modern L lens, you're paying for weather sealing and a quieter USM motor, so not all of that $500 is accounted for entirely by the IS-in-lens.
Taking into account the camera and lens systems as wholes, the two different approaches probably come out about equal in terms of cost, all told, for a typical photographer who might have up to 1-2 decent lenses bought in a year. Pay more up front for the complicated body every few years, or pay about the same amount extra distributed over a handful of more expensive lenses every few years instead. Whatever. :meh:
