Hi @yoavgal 
If you are simply looking for a way to associate which property an expense is associated with, then
The Connect Boards Column might actually be a great option for you as it will not only have the name of the item that is getting linked:
Clicking on the linked item will bring up a pop-up so you can see that property’s information directly from your expense board:
If you want to see column information from the other board without having to click on that linked item’s name, then you can always use The Mirror Column as well.
You can of course use The Dropdown Column if you do not need to have a connection between the boards and just want to be able to select a label that shows what property an expense is for 
As for having a fixed list of values, you can add new labels at any point in time to The Dropdown Column to account for any new properties!
Does this resolve what you’re looking to do? If not, can you expand on what information you need shown between the two boards?
I hope this helps! Remember to mark as solved if this answers your question
Cheers,
Jenna