Promos, Press kits, preview copies etc

[oXdanXo]

Hi guys,

I've been thinking recently, does anyone know how or who gets hold of these "press kits" or even the copies that are "promo not for resale"?
What's the best way for a regular Joe to get ahold of them? I've decided that since the ps Vita is relatively new it would be a good place for me to start trying to complete an entire console of games but promo editions.

So far I only own a few promo copies and 1 press kit which is Grand Turismo 5 Prolouges press kit, but I'm keen to try and get more, but I'm also not looking at spending the earth on them as I've grown up over the past year to realise that I have to pay for food and a house etc. (Bad times when you're renting a flat)

Also why do they make "Press Kits" that are better than the expensive Collector Editions like Halo for example I was gob-smacked at the halo reach and halo 3 press kits.

Also is it just me or do they seem to get more and more extravagent? (Assassins Creed?)
Well I'm at it I know it's not a press kit but how did people originally obtain the Uncharted 2 fortune edition? That's just plain awesome!