Anyone know of a good source for the various plastic fasteners on the cowlings, etc.?

the dealer.
you can get a full set for ALL of the engine covers, etc. for under 35 bucks. i was missing 60% of mine and just went to the dealer and got them all a few months back.
you could also go to the hardware store and get replacement bolts- if you search around there are a few threads talking about this- i believe lowes carries a bunch of machine screws that can be used as substitutes.

i believe lowes carries a bunch of machine screws that can be used as substitutes.

This is true.
http://i102.photobucket.com/albums/m96/lmaoxfilip/TT%20pics/100_5747.jpg
http://i102.photobucket.com/albums/m96/lmaoxfilip/TT%20pics/100_5756.jpg
http://i102.photobucket.com/albums/m96/lmaoxfilip/TT%20pics/100_5758.jpg

For a present I got the kit from 42DD it's arouond $100, a bit spendy but look cool!