^ At this point in your game, I'd certainly be seeking out Calculated Shipping. I was starting out a year ago, and have used Calculated shipping for just about everything. I've made ~125 sales or so. Things definitely still sell.
If you're selling smaller sealed sets, and have planned properly by reading these forums, you'll already have the boxes you're using to ship with. Measure one for parcel dimensions, then simulate a finished parcel (packing materials etc) with each set you're selling and weigh them... record it with your dimensions. Then just plug that info into the shipping information when you post or edit your listing.
Like Phil said, a little bit more work up front, but work you'd end up doing at the point of sale anyway (to print your shipping label). If you're making ~$40 sales, and paying ~$50 to ship to the other side of the country.... even if you acquired those sets for free, you're not eating into your profits man, you're eating into your original capital. Pretty sure that's bad for business. Calculated Shipping ftw.