Hi Mike look here for a quick explanation of different quality UV filters.
http://www.centre.net.au/Filters_0007LG.html
This is where I got mine. You can pick from $20 to about $80. As usual you get what you pay for. Depends on use. It is always better when taking star images to remove any UV filters. The real advantage of the multicoated UV filters is to stop flare from bright sources. The optical quality is also better. Whats the use of an exquisitly crafted lens better than 1/4 wave and add on a filter that is many waves from flat and or parallel.
Hope this helps.
Bert