Order cheap goods from China using AliExpress. Keep the AliExpress app on your phone at all times, order something as soon as you notice you need it. Prices are extraodinarily cheap, but delivery times can be ~2 months, try to think ahead.
Penny’s/Primark is the cheapest I’ve found anywhere.
It may be worth your while to buy a flight to a European/American city, and make your expensive purchases there.