Counting Uniqe values with criteria

I am trying to identify the unique customers that have purchased a product. I have tried multiple formulas (see below) however I cannot get any of them to work correctly with multiple criteria. Below is my data set:

Data Set
Item Customer
a 8089
a 8089
b 8089
c 8089
d 8089
a 8089
a 8089
a 8089
a 9337
a 13514
b 13514
a 26048
a 26992
a 29684
c 29684
a 29984
a 30926




The resulting answers should be:

Item Distinct Customers
a 8
b 2
c 2
d 1


The challenge is applying this to a very large data set (100k+ lines) and I hate "breaking excel" as I do far to often by not using streamlined formulas.

I would use a pivot table...that's what they do.....if you need help on that let me know.

right....I caught that....you could use the remove duplication using the column B as a sort then pivot....I guess it depends how often you have to do this..

are each like a 8089 all in the same cell?
are you not able to use the filter >> advanced to post to another location unique values only?

I'm having trouble following. If you can create a unique grouping of everything you can then set up another area where you've summed each unique item and work from that. Maybe a sample spreadsheet with confidential / sensitive info removed would help. Go advanced and manage attachments for that.

always fun to figure it out on your own....way to persevere...