... I haven't boogered mine, but would like to have an extra to play with. ...
You've stumbled upon the main reason the company is reluctant to sell that part to the public.
As it was explained to me, why would they want to needlessly expose themselves to the potential for someone to "play with" a sear, and then maybe sue the company if & when they experience a problem with the modified part, particularly if they injure themselves or someone else due to a dangerously modified sear?
FWIW, they're very careful even sending such parts to currently certified armorers.
Here's the thing, though. Considering the cost of a complete factory sear housing block costs less than $20 to an armorer, it's easier to simply stock & sell the
complete assembly for both the company & armorers.
After my first armorer class for the M&P pistol I bothered to stock some replacement sear
plungers & springs. The original parts were really small, easy to lose during a full inspection/service, and I thought it might be easier to simply replace aging plunger springs at some point for preventive maintenance.
Now that the standard sear plunger & spring is larger, it's less easy to lose, as well as the spring being stronger, I don't see a need to bother stocking those individual parts. I'll just replace the whole assembly if a problem develops. Easier & faster.
Extra sears? Even as an armorer I don't bother to keep any as "spares", and for the same reason. If one ever requires replacement for repair purpose (unlikely), I'll simply drop in a complete new sear housing
assembly. Again, easier & faster.
Now, companies can always change their minds about their policies and practices. There's been some talk about maybe changing the way they sell some parts at some point in the future, but you can bet they're going to rely upon advice from their legal counsel no matter what they do.