So, when you reach level 80 you obviously have a bunch of level 60-79 greens and a few rares maybe. You probably have a bunch of karma aswell and atleast 2 gold. Now you're all like, hmp how do i get geared up. You can easily get decent geared in this game, there's a vendor in your factions headquarters you picked to join in your Personal storyline. (For example the Vigil Keep) There you can buy a bunch of Power/Vitality/Toughness gear that is level 80 rare for only 15-30 silver a piece and you can also buy weapons there (They have apparently disbaled this now), Rare lvl 80 gear with different stats can also drop in Orr and other high level zones.
To get exotics (Highest quality gear) though you either have to craft for high-end materials that you find in high-level zones. Do explorable dungeons to get dungeon tokens and then buy armor and weapons of vendors, or capturing temples in Ruins of Orr by doing chain events and killing the boss in that temple to spawn Karma vendors there that sell exotic armor for 42k per piece. (There are 5 different temples that you can capture and defend in Orr to keep the karma vendors up, and they sell different stat combinations of gear) This is basically the end-game PvE content along with dungeons.
Level 80 Rare runes, sigils and jewelry like amulets and rings can either be crafted or dropped in high level zones. Exotic runes, sigils and jewelry other the other hand, is only craftable or you can upgrade them in the mystic forge, so for example if you've 4 80 rare rings that has dropped, then you can throw them in the mystic forge in Lions Arch, and you have a chance to get an exotic ring with random stats. You can do the same with weapons and armor that is rare, and you can upgrade Masterwork items to rare aswell, I'm not sure what the percentage is though.
There's one more way to get gear, and that is through WvW, i will start with the karma vendor that stands in your main base in WvW. He basically sells lvl 80 Fine, Masterwork, and Rare armor and weapons for karma the rare armor is slightly cheaper than the exotics that you can buy from Orr. BUT here you can also buy rare rings, amulets and accesories , all these rare pieces are around 15-30k karma each. And there's also 2 other vendors that sell exotic gear for badges of honor that you get for doing WvW when you kill people etc, these vendors sell weapons, armor and jewelry aswell but in exotic quality for badges of honor and I'm pretty sure these are the only vendors in GW2 that sell jewelry at all, and these are located in the WvW maps in your home base.
And for people that doesn't already know, items with the same quality and level has the same stat amount, but different stat combinations. So for example.. a level 80 rare has the same stat amount as another level 80 rare but different stat combinations. And with all this information, you can also sum up that cultural armor and weapons are not worth buying for the stats.