Engineers at eBay are putting the final touches on a controversial media auction system designed to allow buyers of national TV ad time to bid for slots via the Internet, writes BrandWeek.

Launching in a few weeks, the system has signed on a handful of blue-chip advertisers including Home Depot, Toyota and Microsoft but has yet to sign on any media sellers.

The system will offer two ways to transact ads: Buyers can issue an electronic RFP, detailing the type of buy they want to make, including the specifics about total dollars available, demographics, daypart allocations and other details. They can also submit written instructions and conditions and can then evaluate seller responses and choose among them.

Some sellers, including the major networks, have rejected the process as something that would commoditize their inventory. The buyers and marketers are targeting cable networks to come on board as the first sellers in the process.

Steve Grubbs of PHD stressed the system is now only in test phase. "It isn't the anti-Christ that some have made it out to be," he said. "It's not about revising the upfront. This is an adjunct, not a replacement, to the sales process."