Here is a guide on how to buy extremely over-powered weapons for characters leveled 28 to 59. This guide takes advantage of the Reduced Level Requirement item property, which is by far the most over-powered attribute there is. You will potentially be able to deal over double the damage that you could with a weapon your own level.
You would expect these weapons to be worth a lot of gold, yet they actually cost about the same amount of gold as godly low level weapons without the level requirement reduction. This is because a level 60 weapon with a Reduced Level Requirement of 14 will still be processed in the auction house as having a level requirement of 60, even though it has a level requirement of 46. So anybody searching for a level 46 bow the conventional way (by setting the Level Range to 46) will not be able to see these over-powered weapons, which is why few people buy them. The only way to find these weapons is by following this guide.
The Level Requirement Reduction can go up to 18, but that's uncommon, so if you're below level 46, you'll probably have to modify the values to get results. Here are some examples.
If you're level 29 searching for bows, set the Level Range to 34, and the Reduced Level Requirement to 5.
If you're level 30 searching for bows, set the Level Range to 34, and the Reduced Level Requirement to 4.
If you're level 31 searching for bows, set the Level Range to 34, and the Reduced Level Requirement to 3.
If you're level 32 searching for bows, set the Level Range to 37, and the Reduced Level Requirement to 5.
If you're level 33 searching for bows, set the Level Range to 37, and the Reduced Level Requirement to 4.
If you're level 34 searching for bows, set the Level Range to 37, and the Reduced Level Requirement to 3.
If you're level 35 searching for bows, set the Level Range to 40, and the Reduced Level Requirement to 5.
If you're level 36 searching for bows, set the Level Range to 40, and the Reduced Level Requirement to 4.
If you're level 37 searching for bows, set the Level Range to 40, and the Reduced Level Requirement to 3.
If you're level 38 searching for bows, set the Level Range to 40, and the Reduced Level Requirement to 2.
If you're level 39 searching for bows, set the Level Range to 44, and the Reduced Level Requirement to 5.
If you're level 40 searching for bows, set the Level Range to 44, and the Reduced Level Requirement to 4.
If you're level 41 searching for bows, set the Level Range to 44, and the Reduced Level Requirement to 3.
If you're level 42 searching for bows, set the Level Range to 47, and the Reduced Level Requirement to 5.
If you're level 43 searching for bows, set the Level Range to 47, and the Reduced Level Requirement to 4.
If you're level 44 searching for bows, set the Level Range to 47, and the Reduced Level Requirement to 3.
If you're level 45 searching for bows, set the Level Range to 47, and the Reduced Level Requirement to 2.
If you're level 28 searching for 1-hand weapons, set the Level Range to 33, and the Reduced Level Requirement to 5.
If you're level 29 searching for 1-hand weapons, set the Level Range to 33, and the Reduced Level Requirement to 4.
If you're level 30 searching for 1-hand weapons, set the Level Range to 33, and the Reduced Level Requirement to 3.
If you're level 31 searching for 1-hand weapons, set the Level Range to 33, and the Reduced Level Requirement to 2.
etc...
Also, the Reduced Level Requirement attribute can spawn on many types of armor as well, but the benefits are not as great, since the item attributes on other items don't scale up at anywhere near the same rate as weapon damage does.
I hope this guide helps everyone out there who hasn't reached level 60 yet!