It is relatively simple to reprice against FBM differently than Amazon, SFP and FBA sellers.
RepricerExpress allows you to Beat, Match, Price above or even Ignore other sellers.
To have RepricerExpress do this for you, you will need to edit your pricing rule to one of the options above.
Find more details in this article or by hitting 'More Info' next to this setting in your RepricerExpress account.
Our Youtube channel also provides a video guide.