Basically I have a stereo system that's not close to my router, that I want to be able to play music from my iphone remotely from. Does the airport express require an ethernet connection to it? Or are there any alternatives that are cheaper?
Ethernet is always more reliable, but wireless is usually fine for music streaming. The Airport has built in wireless.
There is always an alternative to Apple that is cheaper, which usually requires more effort and usually isn't quite as great on the user interface. That being said, which is the most important goal here? Cost or convenience?
You can play your ipod straight into your receiver with a simple cable that splits into two RCA plugs for your receiver input. That would be cheapest. If you want something more sleek, then determine where is your source and how you want to play it.
In my case, I bought a soundbar with bluetooth, so I can just play anything I want from across the room on my ipod without worrying about networks when it comes to straight audio.