"Replica" is often code for "counterfeit," which raises both intellectual property and criminal law problems. Specifically, you should obtain a license from the source of the goods authorizing you to sell the replicas.
The reasoning behind it is that in making your sales (and your profits), you are trading off the better-known intellectual property, marks and designs of the other company. It's not fair for you to profit without giving the other company something for its hard work, good will and investment in building the brand.
If you sell goods without somehow getting permission, you risk being on the wrong side of an infringement lawsuit--and possible criminal prosecution. You can either get permission directly or confirm with any wholesalers who are procuring goods for you that they have the license to distribute the goods from the source.
Definitely speak to an attorney who knows this area about your plans to make sure you tread carefully.
Nina L. Kaufman, Esq. is an award-winning New York City attorney, edutainer and author. Under her Ask The Business Lawyer brand, she reaches thousands of entrepreneurs and small business owners with her legal services, professional speaking, information products, and LexAppeal weekly ezine. She also writes the Making It Legal blog.