I don't think that you should really list both sleds in your valuation - since most empegs are sold with 1 sled, one should be assumed with the empeg. A missing sled devalues an empeg less than an extra sled typically sells for - many people already have spare sleds or docking stations that can be filled.
That being said, I think that your empeg valuation is a little low, you didn't mention the extra remote or lenses, and the spare sled might fetch more than $100. Not enough original tuners are sold to really settle on a price - the market is fickle. However, given the current exchange rate Patricks kits are ~$210. Figure $75 for professional assembly...

I don't think that you're too far off the money. I think that if the items were split out that they'd easily fetch $1k. He's limiting his market by selling it all together, but I think it'll sell.