A few words on how I imagine the work relationship with the employer:
For projects in the sub 100 USD range I expect to spent at most three to four days for the complete project life cycle, starting with the project awarding and ending (usually) with the payment. This means that as soon a project tie is struck, the work is often completed within one or two days, plus one day employer check plus one day payment. (*)
For this time frame to be upheld it is obviously necessary to stay in (at least) daily email contact with one another, possibly half-daily in case of "opposite" time zones. A longer project time span than four days does not make much sense from the efficiency point of view. (My targeted monthly income is more than 2000 USD, which when scaled to a 100 USD project leaves not much time to be spent for it.)
For serious work (> 2000 USD net value), it is likewise acceptable to spent a month or more for one project.
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(*) Of course if there would be bugs they would be cleared even much longer afterwards, but I expect this not to be necessary. Besides special arrangements on the time might be appropriate for individual projects.
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When contacting me by messenger, after we have appointed a meeting, please note that the connection to the chat server sometimes breaks unnoticed. Please, in such case, try by skype or finally write an email in order to avoid unnecessary disappointment for both of us. One all to easily concludes that the other one has bailed out, though indeed only a technical error occurred.