Everything about getting attention is more interesting than the thing that actually matters. The thing that matters is whether anybody comes back.
The arithmetic, plainly
A buyer who came once bought one thing. A buyer who comes back buys that thing several times over, and the second purchase cost you nothing to win — no promotion, no new followers, no show that happened to reach them.
So the second sale to one person is worth more to you than the first sale to a stranger, because its cost is zero. Put twenty such people together and you have a store with a floor under it, which is the difference between selling and having a business.
They also arrive differently. A regular watches your show because it is yours, bids earlier because they already trust the descriptions, and asks fewer questions because they know how you work.
What actually produces one
Not loyalty schemes. The honest list is short and dull:
The thing was as described. This is most of it. A buyer who opens the parcel and finds exactly what they expected has had the entire experience go right.
It arrived when you said. Or you told them it would not.
The parcel was decent.
They were answered. A question answered in a day, in a sentence, by somebody who clearly knew the answer.
You had something else they wanted. This is the one sellers forget. A buyer cannot come back to a store with nothing in it — consistency of stock is part of being returnable.
What quietly prevents one
A listing that was technically true. The flaw that was in the photograph but not in the words. Nobody complains and nobody returns.
A slow dispatch with no message.
Stock that wanders. A store that sells sarees this month and phone cases the next has no reason for anybody to follow it.
Selling the thing they wanted to somebody else without telling them. If somebody asked about an item, tell them when it goes live.
What to actually do with your regulars
Tell them before you tell everybody. A message to the people who bought from you before a show is the highest-return thing on this list and takes five minutes.
Remember what they collect. Not in a system — in your head, or in a note. "I thought of you when this came in" is the whole of customer relationship management for a small store.
Combine their parcels. Later wins in the same show ship with the first, by default with nothing more to pay. A buyer who notices that is a buyer who bids on the second item.
Questions people ask
How many regulars is enough?
Enough that a quiet show is still worth running. For most small stores that is a dozen or two, not hundreds.
Should I offer a discount to returning buyers?
Rarely necessary. They are not coming back for a discount — they are coming back because it went right last time.
What is the first thing to fix if nobody returns?
Your descriptions, every time. Almost all of this traces back to whether the parcel matched the words.
More: repeat buyers, getting your first followers, describing condition honestly, why packing is most of the experience.