Welcome to the world of two/three wheelers maybe even four.
OK I'll bite. First I wouldn't be concerned if you paid too much for a 93 that you feel good riding. Remember it's only $240. Where else would you find a good road bike with 105s for that kind of money. Next if you use it for a while you can always resell it for very close to what you paid in the first place. Try that with a new bike. Cost of ownership is going to be quite cheap. It's kinda like buying a good used car. Enjoy your new to you ride it will lead you to an enjoyable lifestyle.
Now that said if you go to the bike blue book for your bike
http://www.bicyclebluebook.com/Searc...x=20000&type=0 You will see that values run from $248 to $158. But remember as in buying a used car the blue book isn't the end all. It all boils down to if you like your purchase of not. Good luck with your new bike and enjoy the ride.