I have a 2006 Ford Fiesta with ABS, Park brake and check engine lights on. I used a scan tool and I get the error:
 "U0121:  Lost Communication With Anti-Lock Brake System (ABS) Control Module"
What are the options for repairing this? There is a local wreck yard with all the parts but I understand if you replace the ABS module you still need to have it reprogrammed to match the car? Can I get the dash and ABS module, will that work? or do I need the ECU as well? And then will I also need the ignition and key? I'm trying to get it done without the price being more than the value of the car! Any help is appreciated.... 

I don't know the answer to what you are asking but I can say this: 

What I say here is not a recommendation but is legal.   For your age car (pre Jan 2010) the ABS does not need to work for the MOT, even if the car had ABS when new, as long as you have removed the ABS equipment,   Section 1.6 of MOT manual.

This means you would need to remove the wheel sensors and the ABS unit. Of course if you remove the ABS unit you need to put some joiners on the brake pipes where you disconnect them from the ABS unit.  All brakes would need bleeding of course and then you always have the potential problem of snapping a bleed screw.

Of course some people will say it's irresponsible to remove ABS.  But my 2004 VW LUPO has never had ABS on it, so if that is safe to drive with no ABS why would your Fiesta not be safe to drive without ABS.

And then their's the issue of whether you tell the insurance company. Of course they would go mental and using my VW Lupo argument probably wouldn't wash with them as they work to fixed rigid rules/beliefs and can't understand logic. 

My brother has a 2007 fiesta on which the ABS unit has failed. He spoke to two independant garages about getting them to fit a recon unit. Both said that they had had problems with fitting recon units and they would only do the job if they were fitting a genuine new ford unit. They would do it even if my brother supplied the unit as long as new ford one. So it's not that they were just trying to get more profit on the part, they just said they don't want the problems, from previous experience, of the recon unit not working right. 

Have you checked the connector. maybe a dodgy connection - but quite unlikely it is going to be that simple.