The damage on that is not too bad really, and it looks like it has been glued together. As for the keyboard and mouse, try checking the eBay UK as Apple shipped black PowerMac 5400s and 5500s with matching keyboards here. You do see the keyboards quite often and they tend not to demand a very high price (but shipping to the US might).
Alternatively, spray a normal keyboard black!

Click to expand...

The keyboard wouldn't be the type that shipped with Mac TVs, though

When Apple designed the Macintosh TV, their target customers were students who didn't have enough space in their rooms to accommodate, both, a computer and a television set; so they married the two together and shipped it with a space-saving Apple Keyboard II in a black finish.

It may be rare, but I'm not too sure if I'd want to fork out $25 for one in that condition and minus peripherals, though. See if you can bring him down to $10.