where to buy tasty baklavas?

i think you should go in areas where there are higher concentrations of arab speaking people and where you can find dedicated shops. for example in Rue de Brabant there are several good patisserie selling tasty desserts including baklavas, or at the end of Boulevard Lemonnier towards Midi there are also several patisseries.

As last advice why don't you make your own, I tried and it is surprisingly easy with results not much different from what i find in shops (at a fraction of the price)