Mobile Home Feeder Cable for Cabin
If you're running it through conduit, just buy single strand.  It's cheaper.  e.g. this
And obviously you'd be buying this at a proper electrical supply house, not the bigbox since they probably will not have it, and bigbox is really overpriced anyway.   With wires of these sizes, it is not required to buy white or green wire for ground, you can designate that with tape. 

Besides, it'd be murder to pull a 4-wire cable through conduit.  Four single wires will be tough enough!  Might want to bring in a commercial electrician simply for the pull because he has the gear on the truck to do the job easily.