Alfie's Value in Terms of Trade?

I think something like a boxed Bill & Ben harbour friends set or a Donald and Douglas snow plow set along with some boxed engines, new in box, or maybe a boxed angry Gordon... I don't really know it's really hard to determine an item's value in other items. An easier way would be to get an aproximativ value of what Alfie goes for usually and then compare that to the average value of sone other items.
I may be able to do some research using the method mentioned above later.