So to earn $1k in a week (not an unreasonable target), that's about 420 short story sales per day, or 70 novella sales per day. None of that sounds possible for one title unless a miracle happens!
BUT maybe you could expect a quality well-marketed novella to sell around 10-15 per day in a popular niche like a thriller or romance? So you'd need 5-10 titles of similar quality, no duds, to get to the $1000 target?
Does this sound reasonable, optimistic or pessimistic?
How about short stories? With quality short story and good cover you could expect 20 - 30 sales per day? So you'd need a collection of 15 - 20 (but with greater risk of duds.) Again - does any of this sound reasonable or am I being hopelessly optimistic?