FINRA Series 79 License Sponsor Question

I work for a small three person firm that performs M&A Advisory/Intermediary work.  Our attorney has advised us that we need to secure a FINRA Series 79 - Limited Representative license in addition to a Series 63, 65 or 66 license. 

Is anyone aware of an independent broker dealer firm sponsoring and supporting Series 79 licensing and what the available financial arranagements are with such a sponsoring firm?  Ideally, we would like to find a broker dealer that would allow us to pay a flat fee (monthly, quarterly, or annually) rather than a percentage of fees. 

Thank you in advanced for your consideration in answering my question.