Kari,
If you rent, talk with your landlord. He may assist in hiring a professional to treat the building. Maybe you can get him to pay for the first initial treatment and you can then pay the monthly treatment. If you own the building then you should hire someone to protect your investment.
A professional service will treat the perimeter, inside and out, behind your bulkheads, dryers and all areas where the bugs hide.
Depending on the depth of your problem, they may even treat the inside of your walls.
They will then come back about every 4-6 weeks for a quick re-treatment.
When customers bring in the insects you may see some on the floor, but when they go into hiding the chemicals will then kill them.
Get quotes and descriptions of service from several different companies that provide this service.
Duane.
www.LMARIES.com