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 You can then unzip the the XLIFF file downloaded from Gomo and open each one in Virtaal. 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.