Verizon Wireless has dumped the mail-in rebate options on the Palm Pixi Plus and Palm Pre Plus in favor of instant online discounts. The devices are now instantly available for $79.99 and $149.99, respectively.

A Verizon spokeswoman said that there was “a brief period where we tested mail-in rebates on some phones. We have found that online customers expect instant rebates and since this is a very competitive arena in which to do business, we responded accordingly.”

The instant discounts come just five days after Palm lowered its 2010 revenue forecast on the expectation that sales will come in “well below” expected numbers. UBS expects the company to ship between 750,000 and 800,000 units in its third quarter, compared to its previous estimate of 1 million.

The lowered forecast seemed to confirm widespread reports that Palm was having difficulty selling the Pre, which debuted with Sprint last summer. Sales of the Pixi, which came out during the 2009 holiday season, are also under scrutiny.

The value of Palm’s stock has fallen almost 47 percent since the beginning of the year, to $5.96 from $11.23.