Hey, this is something I've wished for as well, but ordering/sorting isn't mentioned in the docs http://docs.shopify.com/api/product and does not appear to be supported by the Shopify Rest API. My recommendation would be to request all products (remembering to use the limit/page parameters described in the docs) and sort/operate on them however you wish once you've pulled them all.
Hope this helps
It's 2020, and I think that the 'order' parameter is not still documented in the API docs, so it is unclear if this is a supported feature.
Shopify staff have posted about the parameter, such as here: https://community.shopify.com/c/Shopify-APIs-SDKs/Sorting-Products-in-Products-json-by-price/m-p/209... .
Could someone from Shopify please clarify if the order parameter (for the REST API products.json endpoint) is supported or documented? Thanks!