If you see it when talking to the gulid embleemer, then the symbol is for platinum. 1 platinum=1000 gold. So you need 2 plats or 2000 gold to create a cape.
I thought the 2 plat for cape was a mistake they were going to change. Doesnt it seem silly that you create a guild for 100g, make a cape for 2000g and then can buy a guild hall for like 1600g?
The sigil traders don't have any celestial sigils, only those who have won in the HOH do, and well, they're selling them for well over 2 plat right now.
I would expect the cost at the traders to be move then 2k, as a guild hall is supposed to be an obtainable goal, but one that does take some time to get to.
Although we're also talking about a guild here. To get a cape my guild had 15 people around the cape emblemer, all giving ideas and then we all donated to the leader to purchase, so it was a group thing. a few put in a few gold, I put in over 900 myself for it, but in the end if a guild gets together, they should be able to buy just about anything.