Spots open up all the time in guilds, you just have to keep an eye out. And yes guilds tend to pick up people that are already around the same gear lvl/progression as themselves because its just easier, but if the player in question is an exceptional player with lower lvl gear then exceptions can and will most likely be made because gear is easy to acquire.
How would they know how good the player is if they never play with the person because their gear is such a low level?
Its all about knowing people and getting known. Start your own guild or put pugs together, get your name out there. If your good people will see that. Gold in this game is pretty useless for the most part, its mostly used to level professions and after that used to buy junk off the AH, other than that maybe for repairs or pots.
If you have the time to raid or pvp thats how you should get your gear, if not then you shouldn't be worrying about buying gear because you dont have the time to use it.