Hello and thank you for your question.
If this is done as a stock sale, then the S-Corp would continue to exist and it would not be a final 1120S return. Further, your friend would have to purchase your share of the S-corp as opposed to your friend just purchasing the customer list. Your friend would then be forced to be taxed as an S-Corp too.
The proper way, if your friend is purchasing the customer list from your S-Corp and nothing else, is to show this on Schedule D for Form 1120S. Attach Schedule D to your final S-corp return. This will both show the sale and close your S-Corp down.
Note that your basis in the customer list is going to be $0 unless you purchased the customer list, inherited it, etc. I assume you developed the customer list in the ordinary course of business when I say your basis would be $0. The full $2,000 would appear as a gain given a $0 basis in the list.
The latest version of Schedule D for an S-Corp can be found here:
Also, Form 8594 should probably be filed for this. The form is here:
You may wish to note that the sale of a customer list can be construed as producing ordinary income as opposed to capital gains. While this is a bit of a debated topic, I personally look to IRC 1221 and consider it a capital asset, but warn you to do so at your own risk. (ie... you would prefer capital asset treatment and not ordinary income treatment).