Starting prices of runes

I am not sure if this belongs here or in the Questions forum (if it does not belong here, mods please move it).

I noticed when i went to the rune trader that she was out of the mesmers prodigy's insignia. I happened to have just salvaged one, but the rune trader only offered me 230g. Why such a low price, if the trader is sold out of them?

Can someone please explain this to me?

The first picture shows what's available:
runes1.jpg

The second picture is what price quote i got from the trader:
runes2.jpg

The rune trader only has what is sold to him by players. If everyone's just merching those runes without salvaging, then he won't have many and he'll sell out of them before the price has a chance to get very high. Looks like that's what happened.

I understand that the rune trader only has what is sold to him by players. Therefore, since the supply was 0, shouldn't the price be higher then 230 - 250? I don't know what the demand is for this insignia, but how would the trader (i.e. game mechanics) know what the demand is either, since he has none available?

Assuming the demand is calculated over a period of time: say i sold him my one insignia for 230. If in the next 2 seconds it gets sold, and i go back to him and try to sell another one, will he offer me 250, a higher price? or will it remain 230?

What if the insignia doesn't sell for 10 minutes, and once it gets sold i try to sell him a second one will he offer me less then 230 because the demand (i.e. timewise) is low?

I'm just curious if anyone cracked it? Also why such a low price for an insignia to begin with? The Paragon Centurion's sells for 1k+. So my question is why?