Interesting asking a bunch of domainers flip may be first choice, if we think of domaining flips so its most familiar
Cursory results with and without biz, still potential upgrade end users for all
[Bing]
flip - 14,500,000 results - flip biz 24,700,000 results
smile - 15,400,000 results - smile biz 7,850,000 results
sunday - 44,700,000 results - sunday biz - 11,000,000 results