The laws of economics are immutable, no matter what your business is, in the same way that the law of gravitation is the same no matter what country you live in.
If there's never going to be a balance, it's because you refuse to raise your prices. Price ceilings which are below the market equilibrium will always, without fail, attract more buyers than sellers. It's an economic fact and it's an unavoidable consequence of holding prices lower than they should be.
For determined individuals, it's entirely possible to wire money internationally and buy up large sums of bitcoins to resell through your service. But doing so comes with risks which cannot be ignored. Unless you can offer high enough profit to justify taking on those risks, I rather doubt you'll be able to attract the supply you want.
I'm speaking not only from an economic perspective, but as an active re-seller of bitcoins. 4% is the bare minimum which I aim to make on any sale, and that's on top of the fees I pay. My average profit is 6-7%, which puts my sell prices at about 8-10% above the spot price on any exchange. And yet I still have a multitude of buyers and probably need to raise my own prices because I ran short on supply just today.
The bottom line is, for 4% it's easy for me to decline your offer. If you were offering at least 6% I could consider it.
Do you seriously think that, no matter how high the price is, supply will be unaffected? Offer a substantial enough profit margin and I can guarantee that those ice cream suppliers would find ways to get more inventory. The same applies to any product or service.