My 91 Vanagon  blew its head gaskets today....

I first lost the waterpump/alternator belt on the Hi-way.
After replace the belts, I forgot to replenish the unserviceable water
tank ..(all of the coolant was in the reserve tank and I thought it
would get sucked back into the football shaped one..

Well after 4miles on the new belts the oil alarm came on...the water
light too..lots of smoke...and a tow home...

I filled up the internal coolant tank at home and started it up....all
of the coolant comming out of the head gaskets....

My guess is the gaskets got burned up from the heat...I hope there is no
other internal damage...the oil dip stick is still at the same level...

Does any one know the cost of new head gaskets ....
also if I bring it into a shop what is a usual cost to replace the
gaskets?

THANKS JOHN...
PS..something happens everytime at CHRISTMAS when Im on the way to
disney with my kids.