Any time you want to manufacture something that "resembles" what someone else has done, you have to tread v-e-r-y carefully. Depending on how close the resemblance, you could be deemed in violation of the other company's trademarks or trade dress. And that's an ugly and expensive lawsuit waiting to happen.
Why? For the very reason that you want your purses to look like the designer's: The designer has the cache, has the popular design, and "what it takes" to sell and make the line profitable. You'd be trading off it unfairly. Consult with a trademark attorney to get the guidance on avoiding what could be a nasty situation, if the designer ever got wind of it.