Until recently factory grips were readily available from midwayusa, s&w, brownells, etc for around $17-20. Now no one seems to have any in stock. New and used grips are often on ebay, sometimes at a premium price, but if you are patient they can be found at normal prices. Grips are also listed in the classifieds section from time to time. 5900 series grips also fit 4000 series pistols. The straight and curved backstrap grips are interchangeable. Simply drive out the pin to remove grip. Use some care not to break off the inner tabs when changing. Look in the magwell (no mag) to see the tabs. Dont let the damaged grips on the one your looking at scare you off, replacements can be had. Hogue also makes wood and rubber grips too..though they are a bit wider than factory.