Is it legal for me to sell homemade purses that resemble designer purses?
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.