Ammo pricing and lack of knowledge are what keep the prices of the Vickers stagnant. They can be easily modified to shoot 54R, 8mm Mauser, and 308, along with their native caliber of 303brit.
It's a prettier gun than the Browning. It is a better and simpler gun than the Maxim. The Vickers was in active service from 1912 through 1970.
For me, the only negative is the tripod. It's unfortunate that the British didn't make a better T&E mechanism.
Use this time (while they're undervalued) to build your parts stash.