The birthstone for March is an aquamarine. The more exspensive one would be the genuine stone which is real and not manmade. The less exspensive one is the synthetic stone one which is manmade. When a stone is synthetic the coloring may be a little different than the real deal but the clarity is usually nicer.
Jasper, and more specifically bloodstone jasper, is an inexpensive and traditional birth stone for March. Aquamarine is a very popular and modern choice, but it is also more expensive.
The traditional and ayurvedic birthstones of March are bloodstone and jasper, the modern one is aquamarine and the mystical birthstone for March is Jade. Bloodstone is associated with the star sign Aries.
The birthstones for March are the ones that are designated for that month. I have never heard of there being two stones, just one. Maybe it is expensive depending on the quality of the stone.
The birthstone for March is AQUAMARINE which is a very pretty blue gem. If you can't afford it or want a less expensive option you can buy a blue stone.