The application is the easy part to buy
A federal trademark application goes to the United States Patent and Trademark Office, and the office examines it the same way whoever submits it. A filing service does not change that review. What it changes is how much of the preparation you do yourself, and who you turn to when the examining attorney raises an objection.
That makes packages hard to compare from the headline price. One includes a search and leaves office actions to you; another includes attorney review and charges for each extra class. The pages on this site set those terms out against each other so the gaps show.