I have never had the power cord or anything else for that matter develop legs and leave in a campground.
As for the price of one $274.78 from Tweetys (
http://tweetys.com/25footpowercordpl...set-50amp.aspx) for a 25' cord with marine connector that works with our trailers.
I did purchase a 25' 50A extension cord last year. Around $125 if I remember correctly. I also carry a 50A to 30A dogbone and 2 25' 30A extension cords. They come in handy for when you don't need 50' and don't want to wrestle the 50A cord and provide a great backup.