Check and see if there's a rebuild kit available for your old one, first. Lots of pumps have them available for $10 or less. Your LBS would probably have to order it in, but that shouldn't take too long.
My Serfas TCPG has been fine ... but they don't offer a rebuild kit. When it starts to wear out I might even check whether another company's pump heads and/or gaskets might fit it. I'm also needing to rebuild my Spec' Air Tool Comp (might not have to do that so soon if I hadn't been using it on both Schraeder and Presta valves) - rebuild kits for that are $3 I think.
Everything I know, I learned by crashing.
2007 Cannondale Synapse Feminine 3 - SI Turbomatic Gel Flow
2003 Trek Navigator 200 - Specialized Jett 155