[ASK] On creating custom sort module

[EmFeld]

I'm trying to make a customized sort module.
Something that will show me all the product at a certain price range.
Say for instance showing all products at the price range of $100 - $200.
After clicking the sort link it shows the catalog page with all the products sorted ASC.

Any suggestions on what I should do?

Already tried adding new function to the supplier class but still not working.

Thanks

[CTDAN]

Have you thought about/seen this?

http://prestashop.joelgaujard.info/module/14-products-filter-productfilter.html

[EmFeld]

Thank you for the respond.
I've seen it and it's nice, but it's not free. I'm trying to develop it myself but am now currently stuck. That's why I ask.