Recurve bows have the limbs of the bow curving away from the archer so that some of the string runs along the limb.
Although recurve bows have been around for thousands of years the recurve bow didn't enter the modern sport of archery until after the second world war. Before then the longbow reigned supreme as the sporting bow. In the photo below it show the 1952 world champion Stellan Andersson shooting an early recurve bow. The world champions before Andersson all took their victories using longbows.
The advantage the recurve bow offers over the longbow is greater storage and transfer of energy from the bow to the arrow or a faster arrow. When the string is pulled back the tips of the bow, which are curved away from the archer is made to unwind. Extra energy is needed to unwind the curves which can become available to the arrow later when the string is released.
From the diagram the yellow would be represented by a longbow, the area shaded in yellow is the energy stored and is available to the arrow. The area in red represents the extra energy available to the recurve bow do the unwinding of the curved tips.
Much of the development of the modern recurve bow took place in America after world war 2. Coming from a hunting background ( American archery is still heavily influenced by the popularity of hunting there) the pistol grip, wood / fiberglass laminated limbs and a cut away for the arrows became standard on their bows. Now all was necessary was to make the relatively short hunting bow, developed to get through the forest, longer for more stability and of a lower poundage.
In the following video Fred Bear talks about the influence of modern materials in the development of the bow. Starts at 5:00 minutes.
With the introduction of Carbon-fibre limbs are now lighter, lower mass means that they can move faster, and again carbon-fibre, along with new alloys have meant stiffer risers (handles) improving stability. Newer, stronger materials have also allowed designers to develop more energy efficient shapes that in the past would have crumbled under the forces subjected to them.
So when you are wondering why one bow can cost so much more then another it is in the materials and fabrication that goes into its making.