What do you by inform your position? Can you give an example of what to look for?
Some recruiters also have access to data from VCs or from other salary reports (there are a number of good institutions that run compensation surveys - access to these usually costs lots of money). Glassdoor is also a good source of data (sometimes) and PayScale is even better.
There is serious information asymmetry between recruiters/employers vs employees, and if information is the best weapon, employees are woefully unequipped to fight that battle.
The risk to an employee is asking for too little and H1B data can help put of floor on that number.
You really only want advice from someone you are paying and who cannot benefit from under pricing you.