At last. I actually did abandon B2 over DO's Spaces due to the lack of this feature, despite the far more competitive pricing on your end. That, and the lack of AWS API support, but that was mostly related to my particular use case, which was the need to mount cloud storage as disk partitions using s3ql which mainly supports AWS, OpenStack and compatible services. It does have preliminary B2 support [0] but it was really hacky and I ended up losing data because of it.
Having a prepaid credit option and the option to use PayPal for such payments like DO does would have tipped me towards Backblaze's favor to the point of trying to fix s3ql's B2 support, though. ;)
If you don't have more than 1TiB, JuiceFS is totally free.
Disclaimer: Founder of JuiceFS here.
> currency conversion is expensive
Backblaze probably won't accept other currencies in 2018. However, we definitely have heard about this issue, and we have a feature in the works to allow you to "load up" your account with an arbitrary amount of pre-paid cash so that you pay ONE transaction fee to deposit (as an example) £250 pounds at once (incurring the £2.50 conversion fee exactly once) and then as Backblaze deducts from this account balance instead of a credit card there are zero transaction fees.
Would that help?
The OTHER reason this is a requested feature is some customers want a "reserve fund" to be used if their Credit Card payment fails, as a hedge against Backblaze deleting their data for lack of payment.