Generally, 1 million rupiah is about £50, so the cheapest I've seen are around £25. That's not bad, but you then need to get them here.
Tokopedia/Lazada/Shoppee etc. use to be a little difficult for making payments, mainly done at the ATM, but it then progressed to being able to use bank transfer and now able to use card payments, though I think only using Indonesian cards. I do still have an Indonesian bank account and have friends in Indonesia, so I might be able to help. It might work out more expensive than is worthwhile though.