User blog comment:Tails365/Skin Price changes/@comment-4434378-20130412140934/@comment-7305443-20130412145127

Unfortunately, I'm sure they pay % fees to card companies (like Visa, Mastercard, etc), so it ends up being something similar to those stores with signs that say something like "Minimum Purchase $10." A couple of my friends own a gaming store and they just get screwed by purchases on a credit card under $10.

However, if missing only a few RP, I'm pretty sure you can still email them asking for that small of an amount to finish something and they'll send it to you. Just somethingn I've heard but never tried, and apparently it can only happen once.