Shipping question - looking for tips/tricks to save cost

I responded to someone that was looking for a specific figure and when I went to calculate shipping it worked out to more than 1/2 the figure cost! I'm getting estimates from ~9.50 on up to ship a single Marvel Legends (in package) between IL & TX.

I've had one suggestion to try putting it in a box within a flat rate envelope but I haven't quite found a box I'm comfortable using that will fit (don't want the package to get smashed....).

Anyone have any tips/tricks on shipping figures cheaply?