I haven't done a lot of trading on deckbox, but I have done 100+ trades through facebook, and have a lot of references there. Highest trade on FB was around $500. I've been trading magic cards online through fb, reddit, and pucatrade (rip) for the past four years as well as selling cards on ebay and tcgplayer occasionally.

If I start a trade with you and you decide that you aren't intereted please don't just cancel the trade. Give me a reason why or a simple no thank you. It's the decent thing to do. Just cancelling a trade is relatively inconsiderate and rude.