Many translation agencies charge per word for translation. The simplest way to get a word count for your Gomo course, so you can get an estimate in advance, is to download the free Virtaal basic XLIFF text editor from https://virtaal.translatehouse.org.
Steps to get a Word Count
1. Open the course in Gomo Authoring and select Translation Export (XLIFF) in the Actions dropdown
2. Set the Target language to be the same as the Current language then click Continue
3. Open the XLIFF zip and download/extract the files from the zip
4. Load Virtaal and search for the unzipped XLIFF files by selecting Open
5. Select the unzipped file and click Open
6. Selecting FIle and choosing "Properties" will give you a word count for that file.
Each topic has its own XLIFF file plus there are some which apply to all topics such as localization-localization.xliff which you'll also want to translate. Most people ignore the localaiztion-errors.xliff file since that just contains technical warning and error messages.