WoW does not have the option to purchase gear, weapons, etc. with real life money. There are some vanity items like pets and mounts that you can purchase from Blizzard but they are just for looks. Blizzard is very anti-gold selling/buying and the trading of in game items, currency or accounts for real life funds is a violation of their ToS and can result in lifetimes bans. Of course, that doesn't stop the gold farmers/hackers.
Once you get to the end game, the "gearing up" process usually involves dungeons to gear up for raiding and then raid drops to progressively gear up for higher raid content. Of course, these are both group activities but I know a lot of people who have played for years and never raided.
As for dungeons, the new LFG feature they added a little while back has made it easier to get groups. It's a nice system that automatically groups people interested in the same dungeon. Que times can be long but if you're a tank or healer, it's almost insta que. Again, this is if you're interested in grouping but you don't have to.
