That's just plain wrong socketed mobile CPUs are nearly as expensive as the motherboards with cpu. Even for older thinkpads like the t430 the CPUs are more expensive than just getting a "new" t430. Besides the price motherboards die more often than CPUs that's why you see horrendous prices on eBay for decent old gen motherboards. It's a problem in theory that gets brought up all the time and just isn't true in reality.
I don't want socketed CPUs I want all the innovation and advantage of an M3. I just want to get a chip and either replace it myself or get it done for 50-100$ in a repair shop.