The 520 is one of my "grail guns", I love N-frames and also fixed sight .357's, for $650 for a nice one I would do whatever I had to do to get it.....max out a credit card, sell something,live on rice for a month, walk to work.......
I have been asking for a "Classic" version of the 520 for some time now but S&W still refuses to make one.....all they would have to do would be to take the new 58 and drill the chambers and bore to .357! The 520's are becoming very collectible and almost priced out of the realm of getting a "shooter" piece since most of them are found in excellent condition being that they were never issued.