What model of rifle and scope is the add is for?
Accuracy is determined by the weakest of 3 areas - Shooter, Rifle, Ammo: Assuming you (shooter) are not the limiting factor, then many rifles can produce 'ragged holes' at 100 M - but if you just plan on buying factory ammo then you may never see this because the factory ammo might be the limiting factor. Sometimes you get lucky and find a rifle/ammo combo that work well together out of the box, but it can be hit and miss with factory ammo. If you reload you will be able to produce very accurate ammo, and the limiting factor will likely be the rifle.
Tikka, Savage, or Remington rifles are likely to deliver good accuracy. Others too, but these are the rifles I am most familiar with.
As for the scope - you will need to spen at least $350. Falcon has some very nice budget tactical scopes for around $4-500; if you go with a Falcon you will get target turrets which will make it easy jumping from say 100M to 300M by just rotating the knob. Falcon scopes also come with good tactical reticles calibrated in MOA or milrads. You can also get a nice Bushnell 3200 scope with a mil-dot reticle for a good price - the problem I have with the 3200's though is that it is hard to find them with the target turrets - of course you can just remember how many mils to hold over.
If you spend $900 on a rig there is a good chance you won't be happy with the accuracy and will end up trading it for a more expensive rig sometime in the future anyway - so my advise is save your money, wait till you have about $1300ish and buy a nice Tika or Savage with a Falcon scope. That would not be the most precision rig out there, but I would be happy with something like that in my hands. Also, beyond that point you will start spending exponentially more money for exponentially smaller gains in accuracy.