I quote the Trade Licensing Act: "A trade is a continuous activity ... for the purpose of making a profit" ... Your actions, as you describe them, fulfill this - so I highly recommend the CZK 1,000 to establish a trade "to sacrifice". Of course, this also means keeping tax records and paying income tax (I assume that you will do such a business as a side activity, where the social and health care is paid by the "main employer").