Wrong forum to debate buying new versus vintage, and that whole bikesdirect what do you think of them discussion. Google bikesdirect, lots of comments on either side of them.
This is the classic and vintage forum, guess what we like to recommend? But its really up to you. What do you want? If you want a modern bike, with integrated shifters, then a vintage bike could be a poor choice for you (I have integrated shifters on my regular vintage rides, but that was a fairly expensive upgrade). Note, the ones you mentioned above, at the $300 price, are all either stem shifters or downtube shifters. So if you want to go that route, you will need a bigger budget. They start showing up on the various internet branded bikes at about $400 +/-.
As a comparison, road bikes at your local bike shop start around $800. Market price for a good, used, bike shop branded bike, with modern STI shifting is about $350 and up. The better the parts, the higher the price goes.
I am not having trouble finding parts for vintage bikes. I have about 50 vintage bikes right now, and have had a couple of hundred more in the last several years. Today I was working on a mid 1980s Raleigh for a friend. Used the regular parts I use on just about every bike I work on.
The harder you look, and the more educated you become, the better deals you will find.
Last edited by wrk101; 07-05-11 at 05:53 AM.