Obviously there is a limit to how much money any of us wants to spend on jewelry - even wedding jewelry. For some it might be millions and others it will be much, much less.
If you are guessing that it is easy to find high quality diamond jewelry if you are willing to lay out the big bucks you are right. However, your quest for high quality, less expensive diamond jewelry starts with observing what design details are present in more expensive diamond jewelry.
Start by looking online. Cartier and Bvlgari are two excellent places to start. View their diamond jewelry and observe what design details you notice that sets them apart - this is not about the size of the diamond - rather how are the diamonds set or arranged in the band or what precious metals are used.
Visit some chi chi jewelry stores in your local area and examine some fine pieces of jewelry in the flesh - then migrate down to JC Penneys or a similar department store and see what design details are missing or present.
Look over your notes and use your observations to buy the best in your price range.