I couldn't get the search parameters to work. But here maybe a different way for you to think about this.
If using the out of box search filter (ID: pricerangefilter) and add the above options, when you choose the first option, the URL would be searchtext=&searchmode=anyword&pricerangefilter=0;
If you chose option 1 and 3, the URL would be
searchtext=&searchmode=anyword&pricerangefilter=0;2
So maybe your code would be changing the filter options instead of change the actual URL query.