It's a good time to be a seller and a not so good time to be a buyer when it comes to used-car prices.

Although prices for used cars dropped late last year, demand and tight supplies have been driving prices back up since the beginning of the year, the Wall Street Jounal reported.

Especially popular among buyers are used SUVs, reflecting lower gas prices.

The Cash for Clunkers program helped drive prices up as well. Used cars traded in to dealers for the "clunker" incentive were destroyed, reducing the number of used cars available on the market.

Combined with the new cars that were flying out of dealerships and automakers cutting production, used-car prices were pushed to the highest levels in years.

The 14-year-old Manheim Used Vehicle Value Index, one of the most widely followed measures of used-car prices, is likely to hit a record when data for September are released in early October.

The supply of used cars isn't likely to be increasing any time soon either. Thomas Webb, chief economist for Manheim Consulting, told the Wall Street Journal that the unbuilt cars and trucks of 2008-09 will have an even bigger impact down the road.

Without those two- and three-year-old vehicles in the market in 2011 and 2012, those looking to buy used cars will find shopping even tougher.

"In terms of wholesale supply there is still going to be a problem," Webb said. "If you go further out it becomes worse in some aspects."