You can achieve fairly high end sound for medium or low end cost if you match any decent speakers properly to a decent amp and focus on good speaker placement within the room
Most systems sound "high end" when speakers can be placed at least a few feet away from walls to avoid early reflections. In general, most speakers sound better when given some "room to breathe" in this manner. Avoid speakers that are too big in a room that is too small. Most decent, smaller "monitor speakers" work well in a variety of room sizes when paired with a decent quality matching amp, like a NAD (warmer sound) or Rotel (more detailed/transparent).
Then add some decent interconnects (anything other than stock cables that come with units, DNM, audioquest or MIT among others are safe bets) and any decent Monster power conditioner and you should be 90% there. Everything from here is a tweak to your particular tastes. If you are using a phono, make sure the cartridge is properly aligned and matched to the phono input properly.