Skin depth in Silver at 30 MHz is about 11.6 microns (0.4 mil). At 3 MHz, 3 times that (*sqrt(10)).http://www.microwaves101.com/encyclopedia/calsdepth.cfm
So if the plating is 0.4 micron, as given by KA4POL, you might as well not plate, because that's not even 5% of the skin depth. Most of the current is flowing in the copper. And if you had a nickle plate on the copper before the silver, it's even worse. A nickel "flash" is often done to help the adhesion, if it's going to get at all hot. (and if you're plating aluminum, for instance in waveguides or chassis, they almost always do a nickel flash, because the copper diffuses into the aluminum)
Start getting up into UHF and it might be more worthwhile.. 300 MHz has a skin depth of 3-4 micron, so a really heavy plating would help. At microwave frequencies (say, 7 GHz and up), silver plating is definitely worthwhile (at 30GHz, 1mm wavelength, skin depth is 0.4 micron)
The real advantage of silver (or gold) plating is that it is easier to solder to, because either it doesn't corrode/oxidise as much and if it does, the flux cleans it up much easier than copper oxide, sulfide or carbonate, all of which are very tough.
you might also look at:http://www.w0qe.com/Technical_Topics/inductor_Q_tests.html
Silver does look pretty though..