if($this->getProperty('sm_price')){
            $params = $this->getProperty('sm_price');
            $q = array();
            $q[] = "Product.resource_id = {$this->classKey}.id";
            foreach($params as $key=>$p){
                $q[] = 'Product.sm_price '.$key.' '.$p;
            }
            $c->innerJoin('ShopmodxProduct',  'Product', implode(' AND ',$q));                        
        }else{ $c->innerJoin('ShopmodxProduct', 'Product'); }

{$params["sm_price"] = [">=" => $prices.0, "<=" => $prices.1]}