Moving ethernet to wifi

I have a project that works using an ethernet adapter. I want to switch it over to use wifi; I want it to be as inexpensive as possible... (I found this) Unfortunately the end result needs to be configured by code (reading an SD card). using that wifi/uart adapter, it looks like I must configure it manually before using it. Is there another way I could get a wifi connection going (w/o using shields...)

A wireless router can be configured to act as a client in a bridge between the two wireless networks. Some routers are large and have multiple ethernet ports, others like the 703N are small, but "challenging" to setup.

The problem I have using that approach is that it requires something to be preconfigured; I need to configure it (ie: ssid/passphrase) by reading an SD card...