i guess you overvalue the sale here RorrKonn. Yes you may be able to hit that mark you target...
BUT: It is a hell of work! You need to keep on posting items, no day rest. No week holiday. you need to keep on. People keep on buying items if they feel there is value in it. And you gain this only when there is value in it. It is basicly like every market. Regardsless if you sell 3D Stuff or Tomatos: Quality counts. Service Counts. If someone has a problem, you have to react on it. It is a full time job and even more. In my opinion, you may earn more with less stress when you stick to your coalmine idea...
The work that you sell at every market place is only half valued as most revenue is halfed. Also, count sales and reductions etc. You have to accept slow month like summer etc and as already said above: You can never say, what sells best.
Making 1000$ per month is a hard piece of work that really requires you to stay on your PC for the rest of the day. It is not easy, do not think so....

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