Mailing Baseball Cards - Keeping Shipping Costs Low

If you are selling Baseball cards or anything related, heres how to keep shipping costs low (if you're interested):
1) Bubble envelopes are both expensive and inneffective. They do little or nothing to protect the card being mailed. 6x9 envelopes are much cheaper (aprox 6 cents if you buy from "U-Line" online - that's including shipping costs). 6 cents is much cheaper than the 50 cents - $1 you pay for the bubble mailer.
2) Cut up all cardboard you get - especially now that it is the holiday season. Sandwiching a Baseball card tightly between cardboard will protect the card much much much better than the bubble mailer. Cardboard is free. Total cost of shipping materials = 6 cents. Cost to mail will be the same.
3) This should give you the opportunity to pass the savings onto your customers. I can tell you in no uncertain terms that a low "actual" shipping charge is very good for repeat business. Lets not kid ourselves... it doesn't really cost all that much to mail a bunch of cards. 10 cards packaged and mailed securely will not cost more than $2. If you charge somebody $6 postage and the cards arrive in an envelope with $1.50 postage on it, that will turn your customers off. It would turn YOU off if a seller did it to you.
4) Honest shipping is the best thing you can do to set you apart from everybody else selling the same thing you are. Why should I spend my money in your store? It is your responsibility to answer that question for me before I spend my money with you. As the person with the open wallet, I have plenty of options on okay. Make it worthwhile for me to shop with you. I heard somewhere that the most important sale you make is the "next one". It sounds a little cliched but it is perfectly relevant for the okay seller. Do everything in your power to get me to gee back to you. The beautiful thing about okay is that you make money off me even when I don't buy from you, as long as I bid. Every time I bid, you make money. Make it worth my while. Repeat customers are worth ALOT of money on okay.