Hi,
I am not 100% sure, but I think you might have a bug in the way you pass values to the jQuery script of cursor filter ($minVal and $maxVal). the values get filtered correctly, but they do not display well. The minimum value sets to 0 and the maximum sets to the $minVal. I checked the filter class and noticed that you use "explode(' - ',$values)", but the $values are already divided in array. When I uncomment rows 2445 - 2449 (version 1.5.7), everything works perfect.
However I must tell you, that this is really a great script. I really appretatiate the API functionality, which makes the cart so customisable without loosing the possibility to update:o)
Best Regards,
Lenka