There is a varying attitude to PQs particularly among agencies.
Agencies seem to treat you as a misfit. They will insist that their client wishes to have a qualified at a given rate and that there is no room to move. Press them as to why the vacancy has not been filled and you often find out that the salary is not high enough. Yes, as a PQ your salary expectations are lower than a fully qualified but push hard and you will find you fit the bill, and it is the agency who determine the job is for a qualified person. They just have fixation on them.
Salary expectations need to be about 15% below a qualified and if you hold to that there is a lot of work out there. Theexperience you can bring to a job is far often more use to an employer than a wet behind the ears newly qualifies.