bclark,
$600 can be about right for a residential lead paint inspection or survey as it it called, (a surface by surface examination of all the painted surfaces in or on the dwelling), when using a $16,000. Niton handheld XRF analyzer. About 300 readings in 4 hours on site might handle a <2,000 sq.ft dwelling, if its empty. Then it’s back to the office to download the data and print the tables. This old thread might shed more light on it for you.
http://www.nachi.org/forum/showthread.php?t=9042
In our state, many landlords will pay me to have an XRF survey prove that their pre-1950 dwelling is in fact Lead-free, due to remodeling, fire, whatever reason. The XRF machine is the standard means to document Lead-free dwellings. That designation has its advantages here in Maryland for affected rental dwellings.
As always, Lead-free doesn’t necessarily mean free of lead. For that discusssion see the thread above.
hope this helps,
john