A Saudi young man (name was not revealed) gave an interview to Al-Watan Saudi paper after he was recently released from prison where he spent some time for trying to sneak into Iraq to join the jihadists.
Here's a translated summary of what he said in the interview
The man denied the existence of specialized recruiting and smuggling network in Saudi Arabia and he said that Saudis who feel the urge to go to fight in Iraq usually travel to an intermediate country (any guesses?) using tourism as a cover for their real intentions and there they would be met by certain people who organize them into units, provide training and transportation in exchange for a certain amount of money.
The man described the procedures as "primitive and arbitrary" and usually depend on luck and coincidences; men willing to become jihadists travel to town near the Iraqi borders where they are identified (from their looks) and spoken to by the recruiting agents who ask them what they they're doing here and so a deal is made.
For example this guy paid 5,000 Saudi Riyal (~1,700 $) just to be taken 30 miles beyond the Iraqi borders but his journey failed.
Inspite of the high cost of the trip, the new jihadist had to share the transportation with other passengers; he was told by his agent that this is essential to "reduce the cost of the dangerous trip"!
He went on with his story explaining that people's positions and ranks within jihadi cells depends on their combat skills, so those with good skills are appointed leaders for cells working under bigger organizations while those with little or no experience would work under the leadership of a professional commander and he pointed out that cells are usually multinational with members from various countries joined by one goal.
I just want to add that according to an earlier report published by the same paper, 5 Saudis were killed in Iraq during the last week.
Here's the rest of the story but in Arabic.