We have two Major options to buy RUM that cover each and every country possible.
Most are pretty much in comfort with using PayPal and or Credit Card payments that PayPal offers.
For everything else, including big quantities of RUM. We have Coin Payments.
It's a bit more complicated to use, but also gives benefits as a % on top of purchase.
Coin Payments operate on eCoins like Bitcoin, Lightcoin, Etherium and more. It is up to user himself to open an eCoin wallet, purchase eCoins of their taste and buy RUM with them. Using Coin Payments, please be aware of system fees. The quickest and cheap option is Etherium at the time of this post.\
P.S. It would be nice if someone actually wrote some small guides on how to purchase various eCoins in most of the countries using CoinBase, CEX.IO and other trading platforms. And how to properly spent them.