No gear is sold for diamonds (except for wings). But, in ROM gear is the first step. ROM is gear modification game. And to modify gear, you need items from item shop and a lot of them. You can get many of them with phirius tokens but not all, and not fast.
You can buy diamonds from other people, in a way. The way it works is that you never get the diamonds directly. Instead they send you item from item shop which is bought with diamonds. You send them gold.
How you will raise that gold as a free player? Well, lots of time sunk into the process can get you gold. You can gold or resource farm. Friends and guildies can help you. But at some point without good gear, you wont have much to sell, and you wont have good gear without diamonds, either yours or someone elses.
Mounts - item shop. You can get temporary mounts for gold (look for horse tickets in AH), but permanent... you need dias. Again, raise enough gold and you can get them from others.
In my experience, it does not pay. If you possess enough skills and abilities to navigate the game economy and raise gold, you have enough to navigate real world economy and raise dollars. Unless you are a pre-teenager, expect to spend a few bucks.
-- Rustyx --- 92R / 92S / 92M on Reni (Guild KnightShift). Yes, running the new FOTM R/M, cause I am not elf enough to be WD/S.
Oh, and people who have more than 3 classes are clinically insane.