Just got my first O-scope, so in need of a Function Generator! 
(oooooooh its exciting!)
Was just after some advice on if I should go DIY, Kit, Vintage, software etc
Depending on what you want to do you might have little use for a function generator. I haven't used mine for about five years.
I would go for a DIY one unless you have a specific requirement, like a calibrated output.
Will mainly be using for audio applications like setting gain, testing amps, looking at diode clipping and so on.....so only need audible range.
If it is for audio then a good low distortion sin wave is what you need, I would look on ebay for something old but good.
Thanks for coming to my rescue as always Mike!
Tooooooo Ebayyyyyyyy!
There is an arduino dds project that might work for you as well. [ http://interface.khm.de/index.php/lab/experiments/arduino-dds-sinewave-generator/ /url]