BOSTON (MarketWatch) — Call it the Great Rock & Roll Real Estate Swindle. Call it a $26 billion Bait & Switch. Call it the Mother of All Boondoggles.

Call it whatever you want.

But as foreclosures surge again and house prices continue to slide, new data out Monday reveals more of the grim verdict on the $26 billion federal program in 2009 and 2010 to offer tax credits to home buyers.

You may remember that between the spring of 2009 and September 2010 the government handed out credits of up to $8,000 to induce people to buy a new home. It was supposed to gee up the housing market.

How’d that work out?

Gap between younger and older Americans widening

Zillow.com, the real estate information company, says the average price of an American home fell again last month to $171,500 — the lowest level in eight years. That’s down 4.4% from a year ago, although it’s been about stable over the summer.

Now compare the average prices with those that people paid in 2009 and 2010, when they took advantage of the credits.

According to Zillow, prices during that time averaged about $186,000.

In other words, based at least on average prices, you’ve lost about $14,500 — nearly twice the value of the credit. Stan Humphries, Zillow’s chief economist, says the credits, effectively expired in June 2010, when prices nationwide averaged $182,000. Since then we’re down $10,500.

The biggest losers? Step forward all those who took up Uncle Sam’s $8,000 bribe and rushed out to buy a new home in Santa Barbara, Calif. You have already lost $50,000 of your $440,000 investment. And that’s even counting the $8,000 bribe!

Others who are already down more than $30,000 include home buyers in places like San Francisco, Seattle, Flagstaff, Ariz., and anyone who bought down the road from the underground bunker of MarketWatch’s own Paul “The Road” Farrell in San Luis Obispo, Calif.

Oh, and check out Carson City, Nev. The typical homes only cost about $190,000, and even after counting the $8,000 credit you’re already down $8,000.

The IRS says the entire program cost taxpayers $26 billion (though of course it was put on the national credit card, on which interest rates are very low). That money has vanished. It has, as the saying goes, “gone to money heaven.”

Zillow tracks prices closely in 157 cities and major towns around the country. Humphries says that in 110 of those, prices today are more than $8,000 lower than they were in June 2010.

The picture is even worse when you compare prices today with the average for the entire year-and-a-half that the credits were in place. By that measure, prices have fallen by more than $8,000 in about 130 cities and towns.

But look on the bright side. Home buyers in about two dozen metro areas have kept at least some of the $8,000. And in a few — six, to be precise — the market is actually up overall.

Leading the pack? Three cheers for Honolulu. Average prices have risen about $4,500 since the period when the tax credits were being handed out — meaning potential profits on your new home near Diamond Head of maybe $12,500 overall.

If that doesn’t count as a success, I don’t know what does.