First, you need to think about what kind of music you like to listen to, then research speakers in your price range and see what kind of music they are suited to. You then need to draw up a shortlist and audition a range of speakers with your receiver, preferably at home, if you have a friendly dealer that will allow home demos, or in the shop if not. Spend plenty of time listening and don't be rushed or pushed into a choice. The best speakers are the ones that sound best to you, playing your music, not what anyone else thinks is best.
Personally, I like the sound of B&W, Monitor Audio and Vienna Acoustics, the first two of which have good options in your price range, the latter a little above. But as I say, it doesn't really matter what I like.....
Good luck, and I'm sure others will be along who have experience of matching with your particular amplification.