In reply to IainMunro:
I use Asolo 8000s for 5500 to 7000m. They are good for me to 7500m with insulated over-gaiters. The Baruntses seem to be very similar but I have never used them. I do not have any cold injuries.
Whatever you buy will cost about the same unless you find something second hand. It is possible to rent HA boots in Kathmandu as long as you feet are not too big.