However, there's no standalone systems for $500 (as I type). You have to buy one of their bundles which has a controller, or 12M gold or extra game included. So the bundles go for around $550-600.
http://www.bestbuy.com/site/Video-Games/Xbox-One/pcmcat300300050002.c?id=pcmcat300300050002
http://www.bestbuy.com/site/Video-Games/Xbox-One/pcmcat300300050002.c?id=pcmcat300300050002