Airport guest network when the network gets extended I'm looking to extend both the main SSID and the separate guest network from an airport extreme base station for more range. What apple networking hardware is needed? I presume two express would do the trick, one joining each SSID - but wonder if I can do it with less hardware. Advice or tips appreciated.
Apple express would be your best/cheaper option than getting another extreme. You could use third party hardware, but the results are inconsistent as Apples bridging is slightly different to the standard. 

You could use power line networking if you wanted to extended it further than the current wireless network provides. This assumes you're on the same phase of power and wanted to pony up the extra cash.