I'm thinking of starting a little price comparison site, mainly to compare select products at Colesworths vs Aldi (I've just started doing more regular grocery shopping at Aldi myself). But as far as I know, Aldi don't have any prices / catalogues online, so my plan is to just manually enter the data myself in the short-term, and to appeal to crowdsourcing the data in the long-term. And plan is to just make it a simple SSG site (e.g. Hugo powered), data all in simple markdown / json files, data all sourced via github pull requests.
Feel free to get in touch if you'd like to help out, or if you know of anything similar that already exists: greenash dot net dot au slash contact