Collateral is only required to be posted by REC Bidders who are awarded $500,000 of RECs or more. The required amount of Performance Assurance is equal to 10% of any contract valued at or above $500,000.
With regard to your example, no collateral would be required by a Bidder who is awarded $20,000 of RECs, as a contract valued at $20,000 is below the $500,000 minimum to necessitate Performance Assurance.
Please refer to the “Performance Assurance” Section on Page 7 of the Final Ameren Master Rec Agreement PDF posted to the “Renewable Energy Section” of the procurement web site for the language regarding these requirements.