As with selling, there are several ways to purchase items. The bazaar is the easiest and the quickest, shops offer some of the best merchandise, and direct trade with another player works well when the opportunity arises.
Almost every town has a bazaar terminal, large red machines that let you look over all of the items for sale across the entire galaxy. Go up to a bazaar terminal and activate it. Select the category of item you want to buy from the list on the left to view a list of items for sale in the main window. Note the line that says either 'Auction' or 'Instant.'
For instant items, double click an item in the main window to see a 3D view of the item and see its statistics. If you like what you see, click on 'Buy,' confirm, and the item will be deposited into the bazaar's hopper.
For auction items, as for instant ones, double click the item to open up an information window. Instead of 'Buy,' the button at the bottom will say 'Place Bid.' Upon clicking it, you will be able to enter your bid, as well as a higher bid to be automatically made on your behalf if your first one is passed. If you are outbid, or when you win the auction, you will be notified by in-game email, at which point you can go pick up your item.
Important! When you are finished shopping, click on the tab at the top of the bazaar interface that says 'Available Items.' This opens a list of all of the items in the bazaar terminal's hopper. Everything you have purchased will be here, not in your inventory. Select an item and click 'Retrieve' to move the item to your inventory.
There is one thing that you should notice about the bazaar. On the main screen, there are three check boxes, marked 'Entire Galaxy,' 'This Planet,' and 'This Region.' These determine which items you will be able to browse and buy. You are free to look at every item for sale in the entire planet, even in the entire galaxy from any bazaar terminal, and can even purchase them. Note, though, that you can only pick items up from the hopper in the same region where they are sold. If you are on Naboo, desperate for a pair of Pink Jedi Hotpants, and see some for sale in Coronet, you can buy them while on Naboo, but you will have to fly all the way to Coronet to pick them up.
The bazaar might seem like the optimal market for all your needs, but it has one huge drawback. Nobody can charge more than 3000 credits for anything on the bazaar. That means that the really good items will never be for sale there, and you must seek out the craftsman that makes them, or visit his shop.
Because of the price limits at the bazaar, most of the best items will not be found there. Artisans often open their own private shops, or band together to share a shop. Some of these shops carry a whole variety of goods; others might just specialize in one type of item, like weapons or clothing. To find these shops, try asking around. Check to see who made the similar items for sale at the bazaar, and ask them with /tell. Check the official Star Wars Galaxies message boards for the server you are on, as artisans often advertise there.
When you find a shop, it will have an interface almost identical to the bazaar, but with a much better selection of high end goods.
Let the buyer beware. If you are buying from a shop, or especially from the bazaar, use caution! Don't buy anything other than the simplest items without taking a good, close look at them first. Many a person has been taken to the cleaners when a dishonest person has made one of the cheap pistols that everyone gets for free when they start, and named it a 'DX2 Pistol', charging three thousand credits for it. Double click the item in the bazaar, and look at the stats! A quick examination is enough to prevent you from being cheated.
Likewise, look at the condition rating, which should be two numbers separated by a slash (1000/1000). Some people have used a high quality item until it is about to break, and then sold it for full price on the bazaar. Make sure that the current condition is close to the full condition before you buy it. If one number is lower (55/1000), don't pay for it--it will just break when you use it.
Finally, if it is too good to be true, it probably is. There is no Jedi Potion. If you see one, it is likely a beer with a funny name, so put your credits away.