We Need More Writers!
Before I talk about buying gems, I got into the stress test last night and played a norm warrior. Definitely a fun experience, except for when every leap resulted in me dying due to some strange bug. I'd take like 1,000 fall damage every time I used leap, regardless of the distance. Then it started working again after I zoned in and out of the same area. My favorite part of the leveling up experience was running into world events. Leveling became fun and I quickly lost track of time from those battles. Did you get into the stress test last night? OK, back to the buying gems...
Buying gems early on for the purpose of obtaining gold from other players is a TERRIBLE idea. Why? Because the dollar is not going to change in value all that much, but gold will. $10 for gems will always be $10, but maybe the equivalent in gold will fluctuate greatly.
What if at some point the expenses and gold sinks within the game become trivial? If you wasted money to get gems for gold to pay for these expenses that would suck huh? The fact that so many people will be wanting gold means that the value of it will be quite high early on. Then suddenly more and more gold will enter the game, with only a small amount taken out by Trading Post fees and gold sinks. At that point, gold will inflate, and you'll get more gold for your gems than early on.
So a word of advice, don't buy gems and sell them for gold early on. Also, beware buying gems for items you are probably going to get just from playing the game. Save them for stuff you really want and know you don't have the time to acquire!