Running used to be a big part of my life, but due to the miles I put in during my college years, I have too much pain in my knees to do much running anymore. For the most part, I've replaced running with biking. I'm fortunate because in the county that I live in, we have hundreds of miles worth of inter-connected bike trails. This is great because I don't care for riding on roads with other cars. I find the bike trails much more relaxing and scenic.
When I decided to get a new road bike about 3 years ago, I knew that I didn't want to spend much money. I went to a local bike shop with the plan on getting the cheapest, good quality road bike they had. After riding the entry level model, I ended up upgrading one level to get a higher quality gear set and shift levers. All I can say is that I HIGHLY recommend getting a road bike with the gear shift levers built into the brake levers. This was a game changer to me. If you aren't familiar, the brake lever works as it usually would, but also up-shifts and down-shifts by pushing it either left or right.
I ended up with a Fuji Sportif and I've been extremely happy with it. I want to say it was around the $600 range.