What a great idea! Go to the local bookstore and find out which authors are local. Call them or their agents and have one or more of them come to read on the topic of their book(s) (love, marriage, sex, dating, comedy, etc.). You might pay them a few bucks, or you might let them sell copies of their book(s) at the party. Better, buy their book(s) at a discount in advance from them or the bookstore (the discount from the publisher to you direct would be 40 percent or more).
Let them read excerpts. Lots of authors have a great sense of humor and teach on their subject anyway, so you might want to investigate someone local who writes on what the bride is interested in.
Of course, perfect invitations would be bookmarks, book-shaped invitations that open. Party favors could be $5 gift certificates to the local bookstore. (See the section on getting prizes donated for tips.)