shipping quotes and flat rate shipping

Shipping can be tricky on some items, I have always had good luck with USPS. Sometimes I get burned on shipping, a few members actually sent me more money after they seen it cost more to ship which was super cool and nice of them. If I charge too much, then a refund in given. A lot of people do a "flat rate" cost, just the odd shaped, heavy or big items make it hard to judge.