I just noticed a few single speeds around $300.

Scattante Americano: http://www.performancebike.com/shop/...tegory_ID=3040

Mercier Kilo TT, Windsor The Hour, Motobecane Messenger:
http://www.bikesdirect.com/products/trackbikes.htm

Are these pretty shoddy, or are any of them decent?

Also, if I was to do buy a vintage and convert, is it worth it to get a kit like this (Forte $22):
http://www.performancebike.com/shop/...tegory_ID=5129