I use USPS FCDC. $1.75 usually is what I pay for the shipping fee, except for a few relatively heavy ones. Added the bubble mailer, the inside bubble wrap, pouch or gift box and so on, I charge $2.5 for shipping in my most listings.
However, if they choose to use my "eco-friendly" shipping, I refund my customer $1, which means I only get $1.5 for shipping, and I pay the extra $0.25 and gift box/pouch by myself. Sometimes my customers do love this way, and I'm also glad I could do something to protect the earth. :)