There was a great interview with a person who is perhaps one of the main Gaza tunnel bosses. The tunnelling system has now reached a certain level of maturity after the prolonged blockage of Gaza by Israel.
The man very unusually sold his land to have enough capital to open a tunnel and there is free entry in the tunnel market, as long as the local authority, Hamas, is notified and a tax on all goods is paid to them. So it sounds like the market is operating in near-perfect competition terms. I am guessing that some tunnels may well end up coming too close to each other and collapsing, since the strip of land that connects Gaza to Egypt is pretty narrow.
What is very interesting is the fact that the tunnel's construction workers have a rudimentary welfare system in place. You get paid a certain sum of money for injury or death that seems to be set by nobody other than the social custom. Most ingeniously though is that when the tunnel is up and running the original construction workers get a share of any goods trafficked through it. This solves two problems:
1) running a tunnel needs less workers and so the other workers now left without a job can act as very active agents for business for the tunnel
2) The majority of the wage cost for building the tunnel is differed in the future rather at the beginning when cash flow is nil.
I found it interesting to note that the interviewers did not believe that weapons did not get smuggled through but they failed to grasp what the tunnel boss was saying: they were so many weapons that had already been smuggled through that their price was too cheap. This is explained by the fact that guns have a very high value relative to their bulk - making them perfect for their transportation through tunnels. High value low bulk goods are perfect for the tunnellers as there is great profit for minimal problems of running them through the dangerous Egypt/Gaza border strip. Thus too many weapons have been carried through, making them cheaper than in the Egyptian market.
What is much more difficult to smuggle is low value bulky goods such as cement, sand, piping and automobile parts (engines ect). Such material have been banned from entering Gaza by Israel, but because they can only be carried in limited quantities and they give limited value per kg, there is an insufferable scarcity of such goods in Gaza.