>>27725100.22 is a good way to start. Cheap gun, cheap ammo, can do a whole lot of shooting for $400.
A Savage Mk2 with some Tasco glass will get you reaching out to 100m easily, get you started on flinch reduction and proper handling techniques, and for the ~$100 bones you'll have left after the purchase, you can get about 1500 rounds, which can keep you shooting all week.
There are other bolt .22s that are good and cheap, but the Savage is the best of the bunch at a budget.
Avoid semi-autos right now, maybe get one as your second or third rifle. Semis can influence your shooting skills in a negative way when starting out- people are less likely to take care with their shooting when they can just spray and pray. It doesn't happen to everyone, but it happens enough to cause me to suggest it.
Big bores are fun too, but unless you are used to them they may cause you to flinch at the trigger pull, which will drop your accuracy into dindu territory and it becomes a hard habit to break.
In the end, it is your money- find something you like the look of and try it out.
