Advertisement Inc. is releasing two new models of its Kindle e-reader. Both are smaller and lighter than the current Kindle, and one is cheaper because it shuns 3G cellular network access in favor of Wi-Fi for downloading books on the fly.

Here is a look at how Kindle retail prices stack up against those for other electronic readers and Apple Inc.'s iPad:

Amazon's full-version Kindle 3: $189

Amazon's Wi-Fi-only Kindle 3: $139

Barnes & Noble Inc.'s regular Nook: $199

Barnes & Noble's Wi-Fi-only Nook: $149

Borders Group Inc.'s Kobo eReader: $149

Apple Inc.'s iPad: Starts at $499

Sony Corp.'s Reader Daily Edition: $250

Sony Reader Pocket Edition: $150