$20K? The guy spent no where near close to 20K. Where do you come up with this shit UB, do you just make it all up? A Smith&Wesson M&P AR-15 costs about $1100, 2 Glock Model 22 .40 Caliber Gen 4 Pistols? $600 a piece. Remington model 870 pump action shotgun, $300. Tactical vest $156, Shin Guards, $45. Groin protector $10, Leg protectors $150, Gas Mask $100, 100 round magazine $229.95, spare magazines for pistols $90, spare mags for Rifle, $15 a piece. A thousand rounds of 5.56MM NATO, $320. 25 shells of 00 Buckshot, $30. 120 rounds of S&W .40 JHP $60. Ballistic helmet $199. Tear gas Grenade ( not the same thing the Military uses) $16.49
Holmes had No body armor, just padded riot gear type stuff, the helmet was the only thing that might survive a pistol round. All of it for far far less than $20,000.