Cyanide is considered a hazardous waste product, as are most types of chemical reagents. They are subject to both your provincial waste regulations and the Transportation of Dangerous Goods (TDG) Act and Regulations.
Contact a provincially licensed transporter and/or receiver of hazardous wastes and arrange for their proper packaging, transport, and disposal.
Cheap will not be a factor as you will quickly discover after contacting waste companies. If this is in your personal possession, then contact your local municipality for the closest Household Hazardous Waste (HHW) depot.
They are many companies in BC that can receive these chemicals. Check your yellow pages for waste disposal and look for companies advertising hazardous waste. You are legally liable for ensuring proper disposal and for signing a waste manifest (which requires TDG training).