You can't sell/trade as far as i know but you will be able to buy them. Each level you get a loot box, duplicate items you will get gold instead. You can get skins from loot boxes as well as buying with gold. I am not sure how much gold is going to cost in actual money, I am not sure they have said yet. I also am not sure if you can buy legendary skins or not, which those are the good ones that aren't just recolors.
That page works fine for me on mobile Proof but you're right about it glitching on a desktop.
Retired AM Team Raid Leader Battle.Net: Sonick#1178 / Discord: Sonick#7560