I am a lefty, and it is frustrating with the lack of left handed options.
I plan to get a Remington 700 SPS Youth Compact .243 win. The varmint version just weighs too much for what I am doing and probably what you want to do.
Basically I came to the conclusion that because there is just such a lack of lefty bolt actions available, I might as well build one that will do everything I need it to and it will be a rifle that I have my entire life and the last bolt action I need.
.243 is a necked down .308. If I manage to wear out the replacement .243 barrel and feel like moving up to something larger at that point the next barrel would probably be a .308.
If you are looking for something affordable that has great out of the box accuracy, look towards Savage. They have a pretty good selection of left handed rifles as well.