Alternative to paying upfront for SQL server without using hosting provider's SPLA with Microsoft?

Is it possible to pay for SQL server through a third party in the same way you can via your hosting providers SPLA?

For background, we're using AWS but they charge up to 2x more than Rackspace Cloud or Azure would for the SQL licenses on a pay monthly basis (http://ift.tt/1E5NvbK). So I'm looking for alternative options without paying for licenses up front - I still want to 'rent' them.