Most official chart sources are free. Here are the official sources I’ve found so far for English-speaking regions.
US
https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dtpp/search/
Australia
https://www.airservicesaustralia.com/aip/current/dap/AeroProcChartsTOC.htm
The UK site is a little complicated. Click on the eAIPPackage link and the next page has what you need on the left side. It takes a little bit to get the hang of it, but the info is all there.
http://www.nats-uk.ead-it.com/public/index.php.html