First of all, in Mexico they sell 50mg Schering Primo for ~$12-18 per amp, if you do some homework or go to the right place you can find Spanish 100mg Primo for about the same price, but it is not readily available all over Mexico. Therefore, if you are getting Primo domestically from a source who gets their gear in Mx. you're probably gonna pay through the ass for it. Primo also happens to be a top choice for bridging cycles which can mean extended periods of usage (potentially very costly). I don't know about $900, but people who are concerned with quality/safety and use primo, can easily spend as much or more on their primo as they do the rest of their stack.