What companies would order some custom software development? -

Like what is the minimum revenue of the company that would order it? Or what is the minimum number of employees the company ordering it will have? I understand that 1-person or even 5-person company would not order custom software to be written - so what are the minimum requirements to qualify those companies that would order?

There are no hard and fast criteria, Its will depend on exactly what the custom software is required for, what the cost saving will be by having it, and whether it is cost and time effective to have it produced.Small companies, less than 50 may be 100 staff, probably do not have the revenue to buy in completely custom built software but may be able to afford to have a macro based customisation on top of an existing product i.e. Microsoft Excel/Word via Visual Basic macro s as opposed to a completely new spreadsheet or word processor.On the other hand if the developer sees a market for the product over and above a single company they may be willing to develop for a small company on the cheap and retain the right to sell it on their own.