Not a whole lot but I have done it.Same reasons helping to ease the cost of upgrades ,new purchases and weed out stuff.
I've had really good luck using the selling forums.Over all Ive probably sold & shipped about 10 times or so.100% positive results.
I ordered insulated shipping boxes,40 hr heat packs and use USPS as a shipper (half the cost of Fedex) whitch Ive found to be very reliable.They provide, with overnight shipping a tracking number and insurance free up to the first 100$.
One good tip to note. Check to see when the last drop off is accepted at the post office and if you can drop it off a half hr or so before ,this saves up to 8 hrs of the corals sitting in a warehouse unnecessarily.
The cheapest insulated shipping boxes I found from a herb. shop ,bags I got from TB aquatics.
I double bag mine and wrap the heat pack in a single layer of paper towel then tape it to the strofoam lid it should go their because if it gets wet for some reason it wont work.
Also, I was told to poke 2 holes in the strofoam lid to make the heat pack more effcient,something to do with gas exchange.
I dont know how true it is but thats how Ive been doing it.