I certainly believe that SP enjoyed the planning more than executing the plan. It is the planning, any planning, that fulfills them. They hold that as one of their strengths. It is likely their most visible contribution in any endeavor they participate in. They likely attribute all of their successes to their planning and thus plan everything. Even when they try to appear spontaneous they have meticulously planned it. This is the kind of individual MPD should be looking at.
As for spending the money for a one time deal you are looking for someone that always gets the right tools to do the job. They don't screw around with making do with what they have. Do it right or don't do it at all. If it is something they don't believe they have the skills to do they will hire someone with those skills. Money was no object.
I wouldn't presuppose that SP's spouse would ever be aware of the purchases unless they were in on it. I strongly suspect SP controls the finances in their household. I also wouldn't presuppose that any seller would remember these purchases either. It is not as if SP went to a single seller to buy all of these things as I suspect these purchases would have been made across several sellers and locations. SP would be highly inconspicuous in all of this. They wouldn't even be memorable in any way. That is how SP glides through life, nondescript and very often under-estimated. Which is how SP prefers to be seen and which SP uses to their advantage in many facets of their day to day life. This is the kind of individual MPD should be looking at.
You might find that strange. I believe those to be attributes of the person that killed Missy. I could very well be wrong.
Your proposed SP plans meticulously, chooses the right tools for the job etc. (I totally agree) In your line of thinking what is the reason for the apparent lack of firearm?Do you think SP is a felon and unable to obtain one? Do you think that SP is trying to stage a burglary and murders with a burglary tool for that reason? Do you think SP chose the break-in tools for the murder because SP wants to be super close as he strikes MB? What's your opinion on the most likely reason?
This is where I get stuck. The idea that someone so prepared for a murder did not bring a firearm (to complete the LE costume, even) is so off to me. It looks to me that SP is more prepared for a burglary-lurk the halls- kind of thing. Like an anti-social teen who hates his parents or a disgruntled/radicalized type person. A super-smart, ultra-prepared murderer would opt for the least hand-to-hand/hammer contact. The fact that MB could have clearly outrun SP is a huge variable - a prepared SP that knows MB would not rely on the proximity of a foot long hammer to get the job done - if murder was indeed the goal-- in my opinion.