You can own a trademark in the United States the moment you begin using it to sell your products. You do not have to register your mark first. Failure to take this step could lead to a lawsuit and relinquishment of all your profits, payment of the other party's attorneys fees, and complete loss of your trademark. The process of determining whether or not your proposed mark is going to infringe an existing mark is called clearing a mark for use. This should be done prior to using your mark, and again before registering your trademark if there is a delay between the initial clearance and the registration.
C learing a mark for use can be expensive, and possibly time consuming, if it is done properly.
Or, clearance can be done cheaply and quickly. Because the process is inevitably frustrating, many businesses are enticed by the cheaper trademark services that make the whole process sound less complicated than it really is. Sometimes it makes sense to do a cheaper level of searching, but you are almost always far better off paying for a job well done. However, no matter how thorough of a search you purchase, you are always incurring some amount of risk that another company, too small to be picked up on the search report, has been using the mark before you. Even if small, they will have a prior right that will inhibit or prevent your use.