You paid a significant premium for that older memory (a funny paradox of the industry). As P1esk mentioned, you could have gotten 32GB for around the same price. Straight from Dell, paying their inflated prices, on a new R210 it's $173 to go to 16GB of ECC memory.
I've bought a number of large servers recently (using owned servers at colocation in combination with virtual hosts for DR and geo-sharding), and always equip them with 192GB or more. The pricing of memory is so incredibly low it makes no sense otherwise, yet all of these dedicated server vendors act as if 2GB is the norm and 4GB is the advanced upgrade.
I've bought a number of large servers recently (using owned servers at colocation in combination with virtual hosts for DR and geo-sharding), and always equip them with 192GB or more. The pricing of memory is so incredibly low it makes no sense otherwise, yet all of these dedicated server vendors act as if 2GB is the norm and 4GB is the advanced upgrade.