I used to wear my seamaster chrono in the shower every day, and it never ever ever got any moisture in it.
water resistance is the calling card of a quality watch, why spend $60 on a rep, and $150 to get it waterproofed, just buy a better rep.
If you bought a UPO and had it all lubricated, and screwed down hard (incidentally a top tip for making a rep waterproof is to screw on the case back, it isn't screwed on properly at the moment!!) then you will have a water resistant watch!
however if you want to do more than dive and swim in shallow waters then buy a dive watch!!!!
the noob factory watches are used all the time for swimming, and seem to have amazing QC, and like I say my rep seamaster never let me down!