"I'm thinking of either buying 1-2 extra R9 280x cards for mining, or the advanced trade bot instead, does anyone have any idea of what would give the highest ROI? "
Hard to say exactly. Haasbot licence is lifetime, the cards will be good for a few months and then you will need to sell them to get your ROI.
just visited haasbot's website, and it says you get the license for 2 years. Dont have this in my receipt when i bought this a few weeks ago, or any date mentioning when my license is over. Wondering how upgrades from simple to advanced are handled now?