to each his own of course, but I would say go for the authentics. when I first found this board I had nothing but replicas, and after getting more into it for awhile I ended up selling them all one by one and now have 99% authentics in my collection. they're a bit pricier sometimes, but its very worth it.
also like its been said already, ask questions! there's alot of awesome people on this board who know more about jerseys than you could imagine, and everyone would rather see you pick up a good deal than a fake