Having sold a lot of buttons/badges/pins/pinbacks or whatever you'd like to call them, I've talked to a lot of people. Here are the main things to consider when buying buttons:

• Size/Quality: Know how big things are before you order. I've had a few people tell me that my product was "smaller than expected," though I list the size in the auctions. The size, in inches, tells you the approximate diameter of the button.
  
• 1" buttons are the standard size of buttons you will find at retail stores like Hot Topic or the local indie record shop. They are small, which, in my opinion, makes them the most versatile button. You can put loads of them on your lapel, book bag, purse, messenger bag, or hat. As you can see in my picture, they're about the size of a quarter and take up minimal space on my coat's lapel.
• All of the one inch buttons that I've seen are quite nice with a copper spring pin back. Don't bend the pin at a 90 degree angle to attach it to anything, lest it pop out!
  
• There are very few manufacturers of 1" parts and they are all very high quality.
  
• 2" and 2.5" buttons are what I consider old school. My boyfriend has one of an election slogan from the 80s and it takes up the better area of a lapel. More area means more graphic or that it's easier to see from a distance, so if you're only going for one or two (or if it's for your bag), this isn't a bad option.
• 2" and 2.5" buttons can either have a copper spring pin or a safety pin insert for the backing. Some feel the safety pin insert is more solid than the copper spring pin, but I've not had trouble with either.
  
• There are several different manufacturers for 2" and 2.5" parts, so quality varies.
  
• 3" buttons are quite huge. Again, more area means more graphic and better viewing from a distance, but they take up a lot of space. I remember punching 3" buttons in a grade school class with a little plastic machine and I thought they were the greatest thing ever.
• 3" buttons almost always have a safety pin insert for a back. Safety pin inserts are on the upper half of the button and, since the button itself is quite large, this could lead to it flapping about.
  
• The same companies that manufacture 2" and 2.5" parts make 3" and the quality varies on these, as well.

If you are unsure about what size of button you are ordering, check the auction details or ask the seller. If you get a number and are still confused, checking a ruler may help. Also, on an ordinary sized hand, from the tip of a finger to the first knuckle is about 1", add a knuckle to get 2", and the entire finger is 3".

•    Image quality is also a big factor in choosing a button.
  
• Smaller images are usually best for pictures and short slogans, where larger buttons are certainly the way to go for longer slogans.
  
• Be sure to examine the seller's pictures carefully, as well, because over-shrinking or over-enlarging of densely detailed pictures can lead to distortion.
  
• As in all auctions, the seller may not have supplied the "best" image to represent the product, so if you are not sure of the seller's pics, you can always request more. A good seller will be happy to supply more pictures because s/he is interested in sales.