Bien qu'il soit cher, ce piano est d'excellente qualité.
Is it possible to shorten this sentence to the following?
Bien que cher, ce piano est d'excellente qualité.
The sentence would totally be correct this way. Although, you will probably see the first sentence more often than you will see the second one.
Yes, it is possible, the slight difference is that the second sentence is a bit less casual.