Would you buy a used Apple (AAPL) iPad? It seems that the market for used electronics is booming. Much of it is resold to developing countries. But even here in the U.S. consumers are dumping their old iPads and buying the new iPad2, the Financial Times reports.

That sets up a huge secondary market. The big beneficiaries are eBay (EBAY) and the Apple Store. On eBay, for example, sales jumped from 3,300 to 7,700 in a week with prices dropping from $531 to $484 in just one week. If buyers had done some research they could have bought the same unit from the Apple Store for $399, according to the FT.

Best Buy (BBY) is a specialty electronics retailer that competes with general retailers like Wal-Mart (WMT) and Costco (COST), as well as other specialty retailers like GameStop and Radio Shack (RSH). Our price estimate for Best Buy stands at $38.48, which is about 20% above market price.

The company's stock has struggled to gain ground since Best Buy's earnings release in December 2010. Best Buy has faced limited demand for featured products like 3D TVs, and appears to have underestimated competition from players like Wal-Mart and Amazon.com (AMZN).

Barnes & Noble, the Gap, RadioShack, and Sears -- that may sound like the lineup at the local mall, but in fact they are just a few of the retailers scheduled to step into the earnings spotlight this week. Following last week's disappointing January retail sales numbers from the Commerce Department but strong fourth-quarter reports from Abercrombie & Fitch (ANF) and Nordstrom (JWN), the coming week will offer plenty more data on the sector for investors to mull over.

Walmart

Bentonville-based Walmart (WMT) offered free holiday shipping, closed its Moscow office and named a chief merchandising officer during its fourth quarter. Analysts surveyed by Thomson Reuters forecast earnings for that period to come to $1.31 per share, up from $1.17 in the same quarter of last year. The world's largest retailer also is expected to post revenues of $117.7 billion for the three months that ended in January. That's 3.5% more than a year earlier.

Analyst upgrades:

• Netflix (NFLX) upgraded to Buy from Underperform at BofA/Merrill.
• Rockwell (ROK) upgraded to Outperform from Market Perform at Wells Fargo.
• Chico's (CHS) upgraded to Outperform from Market Perform at FBR Capital.
• Ann Taylor (ANN) upgraded to Buy from Hold at Citigroup.
• Meredith (MDP) upgraded to Buy from Hold at Citigroup.
• CarMax (KMX) upgraded to Outperform from Sector Perform at RBC Capital.
• Family Dollar (FDO) upgraded to Outperform from Sector Perform at RBC Capital.
• Siliconware Precision (SPIL) upgraded to Outperform from Neutral at Macquarie.
• Amedisys (AMED) upgraded to Buy from Hold at Jefferies.
• TRW Automotive(TRW) upgraded to Buy from Neutral at Goldman.
• Magna (MGA) upgraded to Neutral from Sell at Goldman.

Analyst Upgrades

• Xilinx (XLNX) to buy from hold at Auriga.
• Orion Energy (OESX) to buy from neutral at Roth Capital.
• Goodyear Tire (GT) to buy from fair value at CRT Capital.
• RadioShack (RSH) to neutral from underperform at Wedbush.
• Novo Nordisk (NVO) to buy from neutral at Goldman.

Analyst Upgrades

• Intel (INTC) was upgraded to overweight from equal weight and Autodesk (ADSK) to equal weight from underweight at Morgan Stanley.
• Citigroup upgraded Blackrock (BLK) to buy from hold.
• 99c Only Stores (NDN) was upgraded to buy from hold at Deutsche Bank.
• PetSmart (PETM) was upgraded to overweight from equal weight at Barclays.
• Piper Jaffray upgraded Ruth's Hospitality (RUTH) and Morton's Restaurant (MRT) to overweight from neutral.
• BioMed Realty (BMR) was upgraded to market perform from underperform at FBR Capital.
• Wells Fargo upgraded Piedmont (PDM) to market perform from underperform.

Several takeover rumors cropped up this morning. One of those is that RadioShack (RSH) is in the sights of many possible suitors. Those suitors include Blackstone Group (BX), Kohlberg Kravis Roberts, Bain Capital, TPG, and potentially Best Buy (BBY).

These rumors had the shares trading higher this morning, which is really a continuation of RSH's longer-term trend. Since March 2009, RSH has trekked steadily higher, overtaking the 10-month moving average in the process. That said, the stock is stuck just below the $23 level.

There's no shortage of headlines lately for big-box retailer Best Buy Inc. (BBY). Not only has the company been linked with the merger-and-acquisition speculation surrounding RadioShack (RSH), but the retailer is also preparing to make its debut on British soil. And, as if that weren't enough, Apple's (AAPL) kind-of-highly-anticipated iPad will hit Best Buy's shelves April 3.

Starting with the buyout rumors, the New York Post reported Friday that RadioShack is "looking to shack up with a deep-pocketed investor." While private-equity firms are eyeing the retailer as a potential leveraged takeover target, the newspaper added. "Another possibility is a merger with big-box rival Best Buy, which lately has experimented with a smaller retail format to meet fast-growing demand for smartphones and other wireless gadgets."