any cheap DAC for my Airport Express?

Bndtracey - You need a good DAC to improve sound quality and to reduce jitter.

Read this airport express review
http://www.stereophile.com/accessoryreviews/505apple/index.html

I highly recommend Benchmark DAC1 to go with airport express. I have great success in this combination.

For a benchmark dac1 review, see
http://stereophile.com/thefifthelement/886/

Ldk

My Setup consists of a Mac Notebook Pro, using iTunes (APple Loseless) to connect to my AirTunes. The AirTunes is connected to a Zhaolu DAC (with Preamp at $225) using the toslink cable and from there to a Headamp Maxed Out amp.

I did many tests, there is a HUGE quality gain by using the toslink output of the AirTunes as opposed to the mini DIN. Also, the Zhaolu DAC offers superb sound quality. May agree that the Zhaolu and the Lavry are superior to the DAC1.

If you really are looking for something cheap that will give you a good bang for your buck you can check out ebay or here for an Entech Number Cruncher DAC. they're older, but you can sometimes still find new old stock. The 203.2 often can be had for $50 or less and the 205.2 typically goes for $100.

I use my Air Port Express with the Spitfire 24 Bit DAC from Firestone Audio. They can be had online for around $250. This made as wonderful improvement over the AE's analog output.

I've been using the original X-DAC from Musical Fidelity (about $150) with my Mac Mini optical output. It was not that listenable until I added a jitter reduction unit from Theta ($125). The results are now very listenable. Read the threads and you may find other options.