A Question About Weapon Upgrades

Hi; I have been playing the game for a month or so and have been confused by the prices of many upgrades. Why do people pay such huge amounts for certain upgrades when they shouldn't be that expensive?

For example, among rangers, people always assume that the perfect bow would have a bow grip of fortitude +30 hp on it. As result this upgrade can demand over 50 k. However, I calculate that a bow grip of shelter (+7 armour) saves more hp over the course of a battle than is gained by the bow grip of fortitude +30; yet this grip only commands 15 k or so. It is madness!!!!

The same is true of monk; elementalist;necro and mesmer staffs; and warrior weapons.

Am I the only one who thinks this is strange?

No your not.

its all about the collector price, collectors usually dont care if the items is extrmely good(in this case fortitude grip), they msotly want the items for the rareness(is this a word?) value