You thought getting the other parts were a pain? Good luck getting an exactra. There's several problems with these.
One - only three possible models have the correct bubble strip.
Two - they hardly, if ever, come up for sale.
Three - when they do, you're fighting other saber builders AND vintage calculator collectors. These people are worse than us. Not only are they die hard collectors, especially of vintage, rare models like the exactras, they will fight tooth and nail to make sure star wars nerds don't get them to take them apart.