By being an online service Landr is a software based solution regarding the way audio recordings are mastered. This is not just cheaper than a studio but by being an on demand solution it is probably even more affordable than most other software solutions. And regarding its features it is real fast. The first step done by Landr is mastering an audio file automaticly. According to the website this already provides acceptable and well done results. This automatic step needs just some minutes. After the first step the result is available to be improved manually.
The prices of the service are staggered by the amount of audio files and the quality of the files to be processed. It starts with a free version rather to give it a try and ends at USD 39.- per month with no limits of files. Further information is available at the homepage of Landr.