Amazon’s AWS cloud computing division today once again dropped the prices for some of its reserved instances, as well as its M4 general purpose instances. For some of these reserved instances, prices are dropping by up to 17 percent and for convertible reserved instances with three-year commitments, prices are dropping by 21 percent.

While Amazon’s pricing structure is perfectly transparent, it’s anything but straightforward at this point.

With this update, for example, the company is not just dropping prices but also launching a new no-upfront-payment option for three-year standard reserved instances. Until now, the only option here was a one-year commitment, but now you can get C4, M4, R4, P2, X1 and T2 instances for a major discount if you are willing to lock yourself into a contract for three years (and if you know exactly what those instance names stand for, you probably work for AWS).

For both one-year and three-year reserved instances without upfront payments (because to complicate things, you also can make a partial down payment for the instance — or pay down the full amount for the complete contract term immediately — and get a different discount) developers can now get discounts of up to 17 percent. This heavily depends on the region you want your instance to run in, though. The 17 percent discount applies to Linux instances running in Singapore. In other regions, the price drop is a bit more modest and falls somewhere between 11 and 16 percent.

For convertible reserved instances — the type that gives you some flexibility over what instance family you want to use over the course of the contract term — the price drops are a bit more dramatic and hit up to 21 percent (once again, that’s for the Singapore region), though in most areas, you’ll see drops between 5 percent and 19 percent, depending on the instance type.

In addition to this, Amazon is also reducing the price for its M4 instances. These are AWS’s most modern general purpose machines. Here, prices dropped 7 percent across the board.