A WORD ABOUT SHIPPING COSTS: I don't make money on shipping. I charge published USPS and FedEx rates plus a minimal amount toward Ebay/PayPal fees (Ebay/PayPal now charges commissions of 10% on each shipping fee, raising the total cost). I ship in sturdy boxes rather than flimsy envelopes.
I've shifted to FedEx Ground services for shipments valued over $200. Delivery may take an extra couple days compared to Priority Mail, but you will pay significantly less for shipping, and your items will be fully insured against loss or damage. (For instance: a 1.5-pound package valued at $250 costs $16 fully insured with signature via Priority Mail; FedEx costs about $11-12.)
International customers: USPS Express Mail includes expedited delivery, $100 (or more) insurance, online tracking, and signature on delivery--and still costs 2 to 3 times less than other international carriers. Express Mail is also the only international USPS method PayPal approves for sellers for items above $200. If there ever arises a more economical option that's safe for both buyer and seller, I'll lower shipping prices accordingly.