I put down the value we paid for it, as for the TV, sure you can bring it if you want. For the electronics, I listed the make, model and serial number. The one computer I brought back, i listed as "home built computer" and what I paid for the parts and the extra hard drives, camera's, etc. I just listed misc. computer parts and what I thought it was worth.
When I went to give him the supporting docs, he said he didn't need to see any of it. We didn't have a lot though, about $10000 dollars worth of stuff.
my experience was great, after all the paper work we still had to get the 10 bags, a bike, 3 carry-ons, a stroller, and 2 small kids, 4 trolleys worth of stuff out the door and they helped us through the door, for heaven sakes.
Just get the forms done before hand and be organized, everything should be good.