need cheap H/W solution for generating DTMF tones

I'm a newbie, looking to build a simple, small and cheap appliance that will receive data input via serial port and then generate DTMF tones through a speaker...the DTMF tones will basically be characterizing the data received, in some sense.

From what I've read, arduino seems well-suited for my project, right?

My question is this -- does anyone have recommendations for the lowest cost hardware that I could use to perform the DTMF tone generation? (Note: DTMF detection is NOT required).

Thanks in advance

Well for a hardware generator you might look into this I2C DTMF generator:

However there is also a Arduino user contributed Tone library that has a DTMF example program, so you might be able to do it all in software: