If you belong to Hilton HHonors, you can use points and stay at the Hilton for free. There are reviews in the Hilton forum on it. I stayed there; it is a pleasant property.

Conde Nast Traveller ran an article on 6 Mauritius hotels. As memory serves, though, they are all at the price point you want to avoid. Regardless, you should find some useful information on the island in the article.