New CLPs can cost between $700 and $1000, depending on where you buy them. My favorite online sources for genuine Audi parts are genuineaudiparts.com and ecstuning.com Carquest's Worldpac line is another good local source.
Used CLPs are certainly available, but I have observed that most of the graphite pumps in most used units are significantly worn and ready to fail.
I provide a replacement part for the broken graphite pump for $65 shipped within the US. (Or for $60 plus actual shipping to other destinations.) You can see a detailed description and photo of my repair part by clicking on the next tab above. I've sold them on the vwvortex.com and eBay for a number of years. I have a Paypal link on the next tab where you can buy one, and you can email me at email@example.com if you need prices for shipping outside the USA or have other questions. As of 10/9/2017 I'm well stocked on these repair parts/kits.
I also have several of the complete CLP modules (all the electronics and the air pump) that have been rebuilt with my replacement parts described above. If the flow chart indicated you have 'fried electronics' then you'll probably need a whole control module. Mine are thoroughly tested to ensure they operate the locks, connect to VAGCOM, synch with remotes, have solid vacuum connection nipples, and properly operate all of electronic features they're supposed to. I provide these for $150 shipped to the US. (or for $140 plus actual shipping to other destinations.) I'm more than happy to program the CLP module to recognize your remote if you send your remote to me.
I can also replace the vacuum pump in your CLP module if you send it to me. Please ensure the electronics in yours functions properly before sending it to me by following my flowchart. I offer this service for $83 ($60 for the upgraded pump, $8 for return shipping, and $15 for installation & testing.)