Hi @johnfontyn,
In general this is not an issue infact its a great feature to define rewards for each product individually so that if your shop contains high priced items the amount of points you want to reward against those would differ from low priced items.
Also to set what is a reward worth in currency you just have to use our free Gateway Addon after that you will be able to set points worth in currency by going in Woocommerce-> Settings -> Payments -> MyCred(Pay With MyCred) click on manage and here you can set the exchange rate of points worth currency. Moreover if you need any further help you can open a support ticket at mycred.me/support and our codex contains all the information about our addons and the plugin itself.
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