Drop Down List for table with non-repeating values

Hello all

I have searched a lot of Google and could not find what I am looking for. It might be possible that I have not used the best words/phrases to search. If so, link me to the thread that contains the same problem as I have. I apologize for that in advance, in case it is true.

Here is the issue.
I have a table where the values for a given column repeat only after a certain number of rows. For eg, I have a field called Priority and it will say have only two values - HIGH and LOW. The values are not repeating with each row and hence a normal drop down will not work.

Take a look at the attachment and let me know a possible solution to achieve this. I would prefer excel formula if possible but VBA solution is fine too. The only thing I cannot do is to create a duplicate sheet or hidden columns with repeated values. All suggestions are welcome though.

Please help!