Meth Decontamination Questions

[Thomas Grove]

At a move out inspection meth paraphernalia was found in one of the units. The property manager had the unit inspected for meth and it came back positive.  "The samples from the property came back at 720.0 µg/100cm²" 

Can anyone tell me about the process?  Estimated time I should plan for it to take and cost?  The unit is around 1500SQft.

What steps can I take to make sure I'm not getting swindled by the decontamination company?  I've been told its a shady biz.