The difference is in the exorbitant shipping midway charges. Kempf's will ship your stuff promptly and do so by USPS, charging only actual postage, and this will end up being much, much cheaper than midwayusa.
Btw, if you want a good do it all, reasonably priced press for your purposes, get the Lee Classic Turret press with the Lee Safety Prime for large/small primers as well as the Lee Pro Auto Disk powder measure. This is a great starter press and is fast enough to provide you most all the reloading you'll need for now and long into the future. It's also a durable well made press. I wrote the beginning reloader sticky and have found this press since then. I own a Hornady LnL, but found the Lee press to be good enough I bought one and use it on my bench. If it and the Lee Classic Cast single stage had been available when I bought my first reloading equipment, I would never had needed any other reloading equipment.
Regards,
Dave