So stop telling your wife stories about how much the new gun costs.
I have an extra M&P 9MM slide (4&1/4") due to buying a PC 5" optics ready slide a year of so back (not, it didn't make the M&P shoot like my P09.)
Since I had that unused slide and I saw a great deal (99.95) for used/trade in M&P complete frames at Aim Surplus, I jumped right on it. $100 for a complete slide in great condition. Why not?
Then I realized it's a non thumb safety frame. All mine have thumb safeties (just like my CZs, FNS, 1911's, etc.) About $28 to Numrich for the parts will fix that.
Then I got to thinking about putting a light on the rail. I have a light. I don't have a holster for the M&P with a light. So, there's the cost of a holster (maybe.)
I've got two other 9MM full sized M&Ps with magazines. But now I'll have another 9MM pistol. So I need more magazines. I can spare a couple from the present collection but I felt the need to order for more. Another $100 and some dollars.
Then there's the great possibility that I'll want to put some Apex parts in it. The trigger and upgrade Apex parts kit will be around another $100.
So, when you tell you wife, "Hey honey, I just got a great deal on an M&P full sized frame for $99. It's only part of the story. Everything else cost about as much as buying a complete pistol.
Same goes for AR15s. By the time you add sling, optics, back up sights, magazines, it's nearly the cost of that cheap AR15 you just built.
Have a great day.