Just go to your local Goodwill, seriously... I have like 15 shirts from Ralph Lauren, Yves St Laurent, Burberry, etc. that were all less than $5 each. All in perfect condition, and I tailored most of them, too. Cheaper than reps (isn't price the main point anyways?), MUCH better quality, and looks a lot better.
Trust me, I've seen some fake lacoste and PRL polos in these stores and they are absolute garbage. The material is thin and weak, there are stitching errors and runners in the fabric, and they just don't have the same overall appearance.