I like your prototyping service, but I have a number of concerns.
Firstly, I like a monthly fixed price model- no variables.
Secondly, I like a good price/performance droplet
say: 3 GByte Mem, 20 GByte SSD, and 1.2 TB transfer; because if you run a 64 Bit wide Linux server, you realistic need 3 GB memory.
Food for thought. Good luck folks.