The diamond anvil and caldron are 700 coins apiece. I bought the golden caldron on sale for 60, but then my purchase failed. Rovio refunded me enough to buy it at regular price, though, so all was good. You could try waiting to see if it goes on sale again.
Also be aware that there is a problem right now (1.0.9) where you will occasionally get 0 stars even with the golden anvil/caldron, but it’s rare.