If you've been saving your pennies for some hard plates, consider the VERY affordable AR500 armor.
Cheap price doesn't mean cheap quality when it comes to these plates.
The plate pictured above was shot with the following at 15 yards with NO penetration:
3 rounds of .223 55 grain Hornady GMX TAP BarrierThe folks at All Shoot Out have a nice review of these plates which you can read here.
3 rounds of .223 60 grain Hornady TAP URBAN
3 rounds of .223 62 grain Hornady TAP BARRIER
3 rounds of .223 75 grain Hornady BTHP TAP
3 rounds of 5.56mm 55 grain Hornady GMX TAP BARRIER
3 rounds of 5.56mm 62 grain Hornady TAP BARRIER
3 rounds of 5.56mm 70 grain Hornady GMX TAP BARRIER
3 rounds of 5.56mm 75 grain Hornady BTHP T2 TAP
3 rounds of .223 55 grain Black Hills Barnes TSX
3 rounds of .223 60 grain Black Hills Soft Point
3 rounds of .223 60 grain Black Hills V-MAX
3 rounds of .223 69 grain Black Hills Sierra Matchking
3 rounds of .223 77 grain Black Hills Sierra Matchking HP
3 rounds of .308 caliber 168 grain Hornady A-MAX TAP PRECISION
10 rounds of 9mm 135 grain +p Hornady Critical Duty
10 rounds of .40 caliber 170 grain Hornady Critical Duty
5 rounds of .45 ACP Federal HST
10 rounds of 5.56mm 62 grain m855
At this level of performance and price, there's no reason to pass these by. Even if you already have plates, consider another set for your spouse, or to keep in your car just in case.