Bezel tension spring question

[Kingface66]

Hi all,
I've been searching for one of these for a 5513, and aside from a dubious-looking eBayer who has one, I haven't had too much luck. Does anyone have a source for these? Additionally, are aftermarket springs of this sort decent? What I mean is, is this the sort of thing where you definitely want a proper Rolex part?....which in this case, seem to be fetching 130 Euros!
http://www.chrono-shop.net/en/bezels...on-spring.html

As always, any and all help is very much appreciated.