I'm not able to put my prismatic philters on the trade broker. I looked and it appears that selling them is possible, but when I click on them, the "Broker" button doesn't light up. Please help, if there's a way.

Usually prismatic philters are 'tradeable', and therefore sellable, but you're probably trying to sell the three prismatic philters you got from the advent calendar and those were made specifically untradeable by the admins. The reasoning is to keep people from making multiple accounts just to get freebies and toss them all on one account, but also to keep the influx of free great items from tanking the economy. To see whether an item is tradeable or not, check its tooltip (comes up when you hover over the item in your inventory).

Makes sense about the free money. Thanks!