Just to clarify - most duties with the USA have now been eliminated. Some exceptions still exist and there are still import quotas in certain categories. For instance, importing shoes or textiles can be cheap on the invoice but the duties imposed can be a real shocker.
There is no PST applicable if you have a retail sales tax license in your province. If CRA charges the PST and the goods are for resale you can apply for a refund.
If I'm not mistaken, the correct tax applied to alcohol and tobacco is an "Excise" tax - it is largely considered to be a "sin" tax that the Feds dreamt up to penalize us for our bad habits. Excise taxes are also charged on our own Cdn. production. The other large contributor to Excise tax is the petroleum industry.
The least expensive manner to have the goods shipped is by USPS if the shipment meets dimensional, weight and content restrictions. At most you will pay a $5 processing fee to CanadaPost plus applicable taxes. The exception will be if the shipment goes by Global Priority as USPS gives these shipments to a courier for delivery in Canada and the customs clearance charges are substantially higher.
UPS is by far the most expensive for customs clearance. FedEx and other couriers are better but usually there rates are higher so it's a toss-up.
If the shipment is large dimensionally, try to find a local trucker that makes routine runs to California. They are very often looking for back-haul to reduce their costs and the rates can be attractive. If it large dimensionally but very light-weight, be sure to tell them that you have top fill and the rates get even cheaper. Try to get these rates from smalller truckers or independants as they tend to quote on a shipment basis instead of a rate card from a head-office.
Good luck.
