The 6 inch dob in the picture above is the minimum scope I could recommend to anyone. Anything less will just be an exercise in frustration with a wobbly scope that will shimmy everytime you touch it or try to focus. What might look reasonably sturdy on the shop floor is a different animal once those wobbles are magnified by 100 or 200 times.
The Orion starblast would be a great starter scope. I would buy one myself if they were available here
