Is this a fair price for my used gear?

This kit new would be about $2350.  $1400 is a 40% discount.

This kit used on eBay would fetch about $1735 - $208 (eBay + Paypal fees ~ 12%) = $1527.  The eBay calculation is assuming close to top dollar of recent completed auctions for the used equipment above.

Since $1400 is within $127 of the maximum of what you could realistically expect from eBay, my thought is that it is a fair price for your used equipment.

On a side note, the Canon lenses seem to have held their value.  The 60D and the Sigma lens are the pieces that have depreciated from age and use.