Betfair Minimum price placed in-play

[osknows]

Betfair has freely available data where the BF minimum price is defined as "Minimum price placed in-play (only bets of a payout of more than GBP100 included)"

Available here http://promo.betfair.com/betfairsp/prices/

Say this value is 4 for instance. It means that potentially a minimum price of 2 could have been matched for only £2. I hope to find a way of circumventing this anomaly

Has anyone got any bright ideas on how to track the minimum price for a defined payout limit? I thought perhaps a combination of the available money multiplied by a factor against the current odds may be a start but am keen on others views

Thanks,
Os