How difficult to prepare feasibility study of small and medium-sized enterprises?

The feasibility study for the small and medium enterprises away from reality and sometimes face difficulties and obstacles faced by small and medium enterprises, notably:

  Institutional and regulatory constraints, financing constraints, the constraints associated with the capabilities of the facility.

Feasibility report has specific components and a man has to search for the data to complete the report. Once the data is available a man can prepare the feasibility report easily.

Generally the data related to small and medium size enterprises is not available which makes the preparation of a good feasibility report difficult.

How long is a piece of string? Is this a financial or a marketing study, based on Region or Global data?

Best thing is to spend sometime putting some boundaries around the idea and then get people in a room to brainstorm the feasibility. Facilitated sessions like this are a great way to drive out various opinions, which you can build into a number of charts or use in simulations (Monte Carlo or other statistical simulation method). Also gives a great sense of risks involved. 

A good return for a day or two's efort.

Its not that difficult; the most important thing to know is that the feasibility study is not a paper stuffed with numbers. After identifying your objectives and the means to achieve them, you need to perform simple SWOT and STEEP analysis (at least as guidelines, nothing fancy). If you are satisfied with the results, and feel that you can take the chance, then and only then you start crunching numbers and do the math for you projected costs and income.