Last week Rdio, added a limited subscription version of its online streaming music service for just $3.99 per month. Called Rdio Select, this is an ad-free mobile plan that combines radio stations and on-demand music streaming. There are no skip limits and music is available on mobile devices as well as streaming devices like Roku and Chromecast. With this plan, users can keep 25 songs at a time to listen to anywhere, anytime, even offline. Rdio Select also features 10-song playlists by genre.Rdio Unlimited is the company’s premium version. At $9.99/month, subscribers can listen to any album, song or playlist on demand. There are no ads or skip limits, and users can get unlimited mobile downloads. In addition to these plan options, Rdio offers discounts for students and families.By comparison, ad-free Pandora One is $4.99 per month. Spotify, which also offers student and family discounts, is $9.99 per month after a $0.99 three-month trial, and Tidal is $9.99 or $19.99 per month. Except for Tidal, each of these streaming music services offers a free, ad-supported version with limitations.”We’re excited to reach a new group of price-sensitive music subscribers with Rdio Select and have designed the service to appeal to a wide audience,” said Anthony Bay, Rdio’s chief executive, in a statement last week. “Rdio Select joins our free tier of ad-supported Internet radio and our premium Rdio Unlimited package. We remain committed to offering customized streaming options tuned to different listening audiences that include the free listening experience. We believe in a free tier that is fair to artists, labels, and consumers alike.”Rdio has a catalog of more than 35 million songs, and the service is available in 85 countries. It was founded in 2010 by Janus Friis, the co-creator of Skype.Insider Take:We are fans of innovation, whether it comes in terms of technology, price or unique products and services to subscribers. Though Rdio is not as well-known as the other music streaming services, we like the product mix – offering personalized, online radio stations as well as on-demand music in free and paid subscription options. By dropping below Pandora’s $3.99 per month cost, Rdio may win over cost sensitive music lovers. We’d love to see Rdio’s subscription numbers, so we can follow the company’s progress, but Rdio has not disclosed that information.