Did I pay too much for repairs on road bike? Should I have bought new?
Bicycles cost money to maintain.  Even if you do all your own mechanic work, you still need to purchase parts.  That being said, more expensive bikes are generally more expensive to maintain at the level you bought them at.  

By this I mean you can purchase a replacement derailleur (of roughly the same quality) for a $250 for perhaps $10 to $20.  If you had purchased a $2000 bike, that "same quality" derailleur may run you $100. The point being, if you had purchased a $700 bicycle up front and done no maintenance, you likely would have spent roughly the same amount of money or slightly more on repairs (based on your description).  More expensive bicycles and parts do not require less maintenance.  

In your case, if you were happy with the performance of your $250 bicycle for five years before you needed to spend money on it, you may have been better off buying a new $250 bike.  ~$50/year for a bicycle that you are happy with seems like a good return.