Since the twink is not the first character on the server, it benefits by having access to lots of wow gold from the main character. So
twinks are generally equipped with the best items available for their level.

Players who spend a lot of time in a particular battleground, make sure they level their twinked character to the max possible level for that battleground, that is, 19, 29, 39, etc. So they would make sure that their character has equipment that is close to that max level.
Selling items that are close to the max battleground levels can sell for a substantial amount. An amount that is significantly higher than
the gold obtainable at the twinks level, because it is the level 80 main character that effectively pays for it.
So there is a market for low level gear that can be sold for high amounts of gold. If you have a high level character yourself, one way of
obtaining gear for twinks is to farm low-level dungeons. This can be time consuming if you do not have a dps based character, and
there is no guarantee of the drops you get.

If your a craftier, creating items for twinks can be very lucrative. It is especially a bonus, if you are still leveling up your character as most
of the materials you need you will obtain yourself while questing through low-level zones. Of course you can buy the raw materials at
the Auction House, but you will find that on the older servers the costs can be high, as there are not many low-level player gathering
materials.

Also, many of the older servers do not have many people crafting for the lower levels, but there are many twinks. So with the rules of
supply and demand, your items should sell for a high price.

Twinks on the battlegrounds are mainly there to get honour kills, so they set-up their skills and talent points for maximum damage. So
gear targeted towards dps rather than tanking has a better prospect of selling. So if you are playing on an older server and have a
crafting skill, you can make a sizable profit if you craft the items that twinks really want.