pricefilter without WooCommerce

You should ACF meta_query to filter custom post type by custom field.

https://www.advancedcustomfields.com/resources/query-posts-custom-fields/

basic example:

$posts = get_posts(array(
    'numberposts'   => -1,
    'post_type'     => 'products',
    'meta_key'      => 'price',
    'meta_value'    => $value
));