Black Glass Terrarium
Same as the bunny I just posted, looking through the companies offers I've found this one with free delivery and 70% off. They have an offer as well which says buy 2 get 50% off 1.
It says delivery cost of £2.99 on this item but when I went to check out the delivery cost wasn't there.
So add two to your basket, checkout then at checkout the shipping should show £0.00 and the promotion applies for 50% off one terrarium.