Clean Podcast Audio File

Can you help? We have produced a few podcast episodes and the sound quality is not great. We really need to tidy it up. We have done a fair bit of editing of files so we are not keen to use the raw file ... (Budget: $250 - $750 AUD, Jobs: Audio Editing, Audio Engineering, Audio Mastering, Audio Processing, Audio Production, Audio Services, Podcast Editing, Sound Design, Sound Engineering, Video Editing)