Mailing:

Mailing costs and protection of your merchandise is a very important issue when mailing sports cards.
You have to balance the ever raising price of mailing with the need to protect what you have just sold.
Nobody wants to spend anywhere from 30 cents to 30 dollars on their favorite player only to have it
arrive damaged from the mail.

A good option for mailing out a precious card is to have the following items available:
1.  Padded or bubble envelops
2.  Hard Top Loader and Soft "penny sleeve" cover for the card.
3.  A hard backing of cardboard to protect the cards.

I find that by packing each card like this has protected them during shipping all over the world. 

Costs:

The best way to purchase these items is to look at buying bulk items.  Try to buy right from the
company or a local store that you can get a deal from.  Or, look around EBay for a good sale also.
I tend to get my padded envelopes from a local store but I buy in bulk.  My sleeves and loaders
were ordered from a store off of EBay.  By buying in bulk you lower your mailing costs.
Be honest with your mailing costs that you charge also.  I have spent a number of auctions trying
to balance my mailing costs out.  I have charged from $1.35 to mail off something (I loose money
due to my supply cost) to $4.00 inside Canada.  I have listened to my customers also.  When they
tell me that $4.00 was too much, I changed my mailing charge.  Research what it costs to mail
things out and try to lower your shipping down as much as possible.  Your local post office
employee's can help you by suggesting the correct size of envelope to use.

Mailing Discounts:

I have also offered a mailing discount for multiple things purchased.  Multiple items
purchased adds 0.25 cents to my auctions.  This covers my top loader and sleeve price, along with
any added mailing costs from Canada Post.

I have noticed a number of places re-charge the basic shipping costs again after X number of
items purchased.  A flat shipping cost to me is the easiest way to encourage people to purchase
from me.  If I know that it will cost me 0.25 cents per card extra I'll just get what I want.  If
it costs me the basic shipping cost again after I purchase 5 cards from you, I'll only purchase 4 cards.

Hope this helps.
Latsyrhc