Best XLRs under $500 a pair

My approach was buying used XLRs from Kimber Kable via KimberKabledirect on eBay.

I tried the Kimber silver streak versus some Mogami and better cable silver serpent and the Kimber's were noticeably better and also about 4 times the price.  

So I searched Audiogon for used cables and looked at eBay and found Kimber very active in selling trade-ins and demos via eBay at about 1/2 list price.  

I purchased KCTG 1 meter and .5 meter XLRs and I view them as my forever interconnects.

A little over your price point, but great cable. Shadow 2 is a pure silver cable at the middle of Dynamique Audio line. I own both the Shadow 2 and Zenith 2 and I'd say the Shadow performs above 80% of the top of the line.

Look into Acoustic Zen Matrix Reference II and Audience AU24 used close to your price range. You got other good suggestions here as well. 
Throw a dart for the choice between the Benchmark, Mogami Gold(similar star quad design) and Belden 1800f all with neutrik connectors. 

Kimber Kable Hero.

Mogami Gold it's probably the best for the price it's not very expensive. XLR cables don't get much better the more you spend. Recording studios use mogami.