I think the first guy was just trying to show you what your choice might be..i.e. limited.
Bailey, I think, has given you the bottom line. The 24" size is in very low demand, hence the limited availabity of choices. This does not help someone like yourself who would like to replace the oven without a complete kitchen makeover. But the hard fact of life is that a manfacturer has to very closely watch the demand volume for his product...be it a $2 widget, or a wall oven. As the demand drops, the variety drops and the price goes up.
I cannot speak for the appliance market...but in my field ( plumbing, faucets,, shower valves, etc) it has certainly come to pass that I can pick up two lavatory faucets from two completely unrelated brands. Different style, different handles, etc. But UNDER the handles and the chrome body.....they CLEARLY come off the same chinese production line.