AD/DA conversion with simple memory interface?

I've spent some time in doing searching and nothing comes up, here as well as on the net, so I'm going to the best sources, human brains.

I'm working on a digital delay, and for a number of reasons I'd like to control operation with a PIC and do the ADDA and memory on the cheap. I'm having trouble finding converters that make this fairly simple. So do you have a pointer to:

- a sigma-delta mod/demod chip with a bitstream output that's not expensive?
- an audio CODEC with parallel outputs/inputs?
- an audio CODEC with serial word outputs that can eat its own output when fed back into its input?

Obviously I'm after quick and only-slightly-dirty delay here, and while I can do the interfacing between chips and memory, I'd like to keep the clot of logic down to minimal.

Any pointers?

How dirty? What bandwidth and delay times?

Say about 80db S/N and the delay time is my option by how much memory I use. The trick is to make getting data into and out of memory easy, and then memory is the only variable.