Used to work for an internet mail order company – 1500-3000 orders a week.
Busiest time on sales
Sunday evenings 5-10. Just don’t coincide with The Voice/BGT/Rugby/ etc etc live show [EDIT which may account for unexpected pittances: but compare with similar products recently ended]
Thursday lunchtimes 12-3 (though this is less so on ebay as your much less likely to have an auction item delivered in time for the weekend but there’ll still be browsers about doing best price shopping searches)
[2nd EDIT – if you list it Sunday mid evening ish on a 7 dayer.. you’ll pick up that weeks browsers, Thursday lunchtime browsers and then catch some of next Sundays too!]