Alfie's Value in Terms of Trade?

If you're confused at the title of the thread, I'm wondering what engine/item by itself (or multiple engines/items combined) has/have the same value as Alfie to be able to trade for it. 
For Example: "Bertram and FF Toby together make up the value of Alfie and can therefore be traded for one". Doubt those two make the value of Alfie so I want to hear from the experts and people who own Alfie.
I think my odds are better trying to trade for one rather than pay and look for one. 
Any help will be appreciated! 
Thanks!

Edit: Knowing trades for him with and without his cargo would also be appreciated!