Priority 3 day mail would be a little over 30 and Parcel Post would probably be about 20. This excludes packaging weight and costs. If you used a crate method then that will definitely add some cost. USPS IMHO opinion is best. Fedex and UPS can be cheaper if you have discounts or can use it through your employer.for a sub thats 30 pounds?
Cut pool noodle around the gasket to protect the surround and something soft, but not completely compressible under the motor. Make sure it fits tight in the box. Double-boxing is not a bad idea.and on another note. Whats a good way to ship a sub. Box way seems a bit spendy to me considering id prob sell the sub for like 150 shipped.
Best i can think of is get a box thats bigger than the sub. Put hard foam on all six sides with the sub in it. Then put it in a nother box with foam in that box with peanuts.