try usedhandhelds.com; they sell a 3-pack of generic one-piece units for $14.95. I have purchased these from them and they fit into my j720 fine. They do not have the spring, but....so what! They work fine!
Good thing I didn't rush out to buy one. My 680e arrived today WITH the stylus tucked in. I guess the guy I bought it from didn't realize it was there.