Just in case anyone is curious, I was talking to my buds at the dealer parts counter today (bought an oil filter), and I asked them how much they would sell a 617 turbo long block for. The gave me a price of $6700 (50K mile/4 year warrantee), which I thought was pretty reasonable (metric motors is about $6000, as I recall). Apparently these are very complete engines (IP, alternator, water pump, etc). He said he just sold some for use in snow cats, apparently the benz price is lower than buying them through the snow cat manufacturer.

I'm not planning on needing an engine anytime soon, but it's good to know they are available.