Yes, there is Topical finasteride available, and you can purchase it online as well. There's one particular website that sells it, but I forget the address. But another website that sells it (and I've purchased from this website before, so they are legit) is http://www.wholesalehairproducts.com
Just a word of caution....topical finasteride is easily absorbed systematically. Results you obtain are due to whole body effect, not local, so there really is no benefit over taking it orally. There have been studies that indicate this.