Small value/quantity trades will most likely be sent in regular mail envelope unless specified. Higher value trades will be sent out in bubble mailers.
I am usually down to look through a tradelist and pick stuff out that isn't on my wanted list to make a trade happen.
When requesting trades with moderately valuable cards please don't expect several $1-$2 cards to do the trick.

Collecting Angels, toss some in a trade for filler if its needed.