Where to find a very good Price Comparison PHP script?

I’ve bought a price comparison WP theme almost a year ago and since then needed to fix a lot of things and I even needed to buy an expensive plugin and invested a couple hundred dollars to make the theme work. But in the end it still doesn’t work properly as the plugins and filtering can handle large amounts of items and wordpress doesn’t allow extern image urls by default. Importing thousands of images would require xxx GBs of server space which makes no sense.

So I came to the conclusion to better build a custom solution and therfore wondered.

Does anyone know a very clean and good Price Comparison php script or ROR that allows to import large amounts of items via xml/csv/api and offers statistics aswell? (from which I could start from)