c# add responsive voice (via api) to site, that allows connection from c# app

Want to integrated Responsive Voice via their API to a software. Most likely the best method is to integrate to a site, that the software will access, this will prevent abuse, and keep all api calls from 1 ip address. Software will need to see what voices are available, and select a default, and then instead of recording voices (via Microsoft TTS engine) will get them via the site. So you need to know enough to code the site page, which will behind a login, and the c# part to access that, and record the TTS or get the sound files and store into the software. Software currently works with Microsoft TTS. Works very well. But since Microsoft limit you on voices, this would give more options. Am open to using a different solution, providing the monthly rates are reasonable. This should be few hours work. If not then you probably don't have the skills for my project. So I would expect something like $100 as a fee. Thanks.