It happens every product cycle. Despite Microsoft's best efforts to keep details of its launch plans under wraps, an online retailer has leaked pricing for OEM copies of Windows 10 and Windows 10 Pro and is even accepting pre-orders.

The details appear at Newegg.com, where a search for Windows 10 turns up two OEM System Builder packages for sale.

This is familiar turf for Newegg, which also jumped the gun with preorders for Windows 8 in 2012.

Assuming the on-sale dates listed here are accurate, small system builders will have access to Windows 10 before Labor Day. But if you were looking forward to a price break, think again. These prices are actually $10 higher than the corresponding prices for Windows 8 and Windows 8 Pro when they were launched.

Just In: Windows 10 to arrive on July 29

Microsoft has already made clear it plans to give away Windows 10 upgrades to qualified users of Windows 7 and Windows 8.1. It's not clear whether the company will offer paid upgrades for those without a qualifying license, or whether full package product will be available for those who are building their own PC or installing Windows 10 in a virtual machine and don't qualify for the free upgrade.

A slip of the tongue from a Microsoft partner earlier this year gave away the launch date for Windows 10, which is rumored to be arriving in late July. In previous product cycles, the gap between launch (release to manufacturing, or RTM) and availability of OEM products has typically been about three months.

If this schedule holds up, the gap between those two milestones will have narrowed to about a month.

That kind of speed is essential if Microsoft expects to deliver on its ambitious goal of putting Windows 10 on one billion devices within two or three years after launch.

Hat tip to @MohammadMSFT on Twitter for the tip.