PC on Globs of Ectoplasm

I'm a selling noob. How much are Globs of Ectoplasm worth and do the prices fluctuate, and if so, how can I know what the value is when I use them for trading?

On a related note, why don't people use Lockpicks which seem to have a fixed trade value of 1200-1250g?

guilds that own a town can buy lockpicks for 1200 gold, and ecto goes for 1k under what the trader is selling it for.

4.7k +/- usually
Depending on the rare material trader sell and buy price

Lockpicks aren't popular as there is a limit to its value as it is about 1/4 the price of ectos. And most trader has been using ectos since GW started.

ecto is not always 1k under trader, most try to sell for 300 to 500 under, you just have to find the people who will sell at 1k under, and they are much rarer