If you are looking for a good filk sampler, an east coast collection that I do recommend is "Balticon Tapes". Its a 2 CD set of about 45-50 songs that samples 25 years of filk performances in the Baltimore area. It has people from all over including Leslie Fish, Frank Hayes, Kathy Mar, Tom Smith, Clam Chowder, and many others.
Its a great way to hear lots of voices and get a start of an idea who you might like. Also, any Worldcon album (on CD or if you can find an old tape) will give you an idea of various performs. Filk convention albums tend to have GOHs on them plus a good sample of the locals to that area at that time.
And if you have not found it yet, 3 other areas for online filk music -
Virtual Filksing at
http://www.prometheus-music.com/eli/virtual.htmlHigh quality filk recordings
Filk Archive at
http://www.filkarchive.org.uk/ (Free membership required to download the mp3s). The site has a mixture of high quality recordings and recent convention recordings to a couple of voices that are very rough.
and
Filk.com's radio station via live365.com where he plays a mixture of what is available in his store and out of print tapes.