The new HTC One flagship smartphone should go on sale in the U.S. by the end of the month, but deals seem to be in place already.

Although the handset is yet to make its U.S. debut, it seems that carriers and retailers are already racing to offer the best deals for the handset. The HTC One apparently comes with extra incentives to motivate potential buyers, making the smartphone even more appealing.

T-Mobile, for instance, throws in a free car dock for anyone who purchases the HTC One smartphone. The car kit allows users to put their handset on the car's windshield or dashboard to use it as a GPS.

The carrier mentions that this is an online-only offer, and duly notes that the offer is available "while supplies last." Moreover, the T-Mobile offer goes with the $100 offer from HTC, in addition to that free car dock. This deal, however, is quite limited.

Potential shoppers interested in taking advantage of the $100 deal have to register before April 4, buy the HTC One before April 26, then trade in their current handsets (in working condition) before May 31. This deal also offers some hints regarding the availability timeframe for the HTC One, at least for T-Mobile.

RadioShack, meanwhile, fuels up some HTC One incentives of its own to rival T-Mobile's offer. This offer applies to customers who purchase an HTC One smartphone with the Now Network, and it's not the first time that RadioShack has made such offers. Those who want to take advantage of this offer can expect to shell out $199.99 for the HTC One after signing a two-year contract and receive a $10 RadioShack coupon and $50 Google Play Store Credit.

News of the RadioShack offer on the HTC One comes from PhanDroid, which received a promotional flyer touting the new deal. The flyer, however, doesn't mention any word on an exact release date.

Meanwhile, it seems that people purchasing an HTC One from Sprint with a two-year contract will receive $50 Google Play Store credit as well, according to AndroidAuthority. This store credit would allow new HTC One owners to raid Google Play for apps, music, books, movies and magazines, getting plenty of content. As most apps are priced at $0.99, users could get up to 50 apps with the $50 Play Store credit. Interested?