Wish it was that easy, if I type in Flash Sale I get a listing of thousands of trivial pieces of crop that are overpriced. No general sale with so much off for such an amount purchase. Maybe someone else has a clue.
I had the same disappointing experience. Tried clicking the drop down list to the right of the search box (initial setting is "All categories") and choosing "business and industrial." Still loads of pretty useless stuff.
The flash sales I always buy from are the $15 off $75 ones, there are others. This flash sale only lasts a number of hours, there is no pre notification for them. They are announced the day of & usually ends at 6pm PT. Usually about once a month but not always & is random. They'll show up on the ebay home page. I hear if you susbscribe to ebay's marketing emails you'll get them but you'll get a bunch of other emails also. They should also pop up in your ebay summary page. You can also check deal websites, they usually post them too.
The others sales they have are like 20% off $25 min or $50 but these are limited to specific sellers and last for a few days. There's one going on right now for Columbus day , ends tomorrow, & there was another for NY Comic Con.
To add, if you buy a lot from ebay like I do, be sure to enroll in ebay bucks for rewards. I just received my rewards for the last cycle which was $32.