How to get a sourdough like effect without the hassle of a real sourdough starter?
You can try a pâté fermentee. This is essentially a dough you leave to prove overnight. It is how most french bread is made. You simply make half a batch of dough, leave it overnight, then make the other half and knead the PF through it. While the flavour isn't quite as sour as sourdough, it does have a bit more of a tang than 'normal' bread.

You might also try a slow, 2 or 3 day prove in the fridge for any bread dough.