I completely understand where youre coming from. The price of everything has just sky-rocketed. Its hard enough to enjoy the sport we love when everything involved is draining our wallets.
Personally, and Im just speaking for myself, I always try and look at the long run. I know that one day I will want a .223/5.56 AR. But I also know that right now im really enjoying .22lr's. They are cheap and fun to shoot. They also enable me to save up some cash so that when the time comes I can purchase an AR. Thats why I look at it the way I do, I could spend a little more money now for a dedicated .22lr M4 from Spikes and later on when I save up more money again, just have to buy the upper of my choice.
But again, I do see your point and have heard good things about the M&P 15-22. I looked at purchasing one myself but decided on the Sig 522 instead. I believe that most of the extractor issues that were experienced by early adopters of the 15-22 have been resolved. The only 2 things I dont like about the 15-22 are, proprietary mags, and that its totally made out of polymer. Otherwise, its a fun gun to shoot.
Good luck in your purchase and please post the results.
G34 OD, G21SF, G17, Advantage Arms LE 17-22 Kit
Sig P226 Elite, Sig P226 .22lr Conv. Kit, Sig 522 Classic
SilencerCo SS 22Sparrow & SilencerCo 9mm Osprey
Hornady LnL AP, 9mm & 45ACP