Like you said, that could vary greatly. A new production pair of TS 6SN7's would run $30, while a pair of NOS TS BGRP can run upwards of $600. I've seen ECC32 pairs go for more than that. This is not even counting the other variants the LG can do.
The great thing with tube roller's amps is that it's totally dependent on what the roller wants to do. The amp can vary depending on what sound you're going for and the cost is totally in control of the roller's hands. The downside is those who just must have the best of everything won't settle until they find the most rare, exotic, and (of course) expensive tubes. People then factor this into the cost of the amp as in "It's $3XXX, but factor in an extra $500 for tubes", and then don't buy the amp because they can't afford the most expensive configuration possible. I've seen this happen with Balancing Act buyers and it is a skewed way of looking at things. A pair of current production EH tubes on the BA is fine, and I'm sure there are many cheap readily available tubes for the LG that will be a knockout.