Ardents right..... 50BMG and cheap or economical don't go together. In all reality if you want to do the .50BMG thing right you are looking at dropping around $8000 to start. Factory surplus ammo is running $9.00 and up a pop with 750 grn Amax bullets around $15 a pop. You may save a few pennies reloading, but commponents are still expensive due to the export ban on all things .50 out of the states.
The .50 BMG is something you realy want to do your homework on before making your purchase. Custom built rifles are available for around the same money as factory builts so something else to think about.
The good news is there is no rush like a .50BMG hitting targets at a couple KM's