If you want to use 4Kn drives, SSDs (w/trim), or easily switch between RAID and HBA modes, I would recomend an R730 with H730 controller instead. They're available on eBay with 128GB of RAM for just over $1,000 USD. If you don't want those features, an R720 is a good choice, and around half the price.
Idle power consumption of an R730 with no drives is typically about 85W, though higher-end CPUs drive that up a bit. The older R720s are a bit higher in the 100W range. When the extended warranties expire, high-spec 2nd hand equipment floods the market.
