This is the part you need to change:
value:value || field.row.Buy_Rate__c, <— the starting value (even though there is 1 bug i did not figure, is that the slider always starts at 0, until I start moving it then it adjust to this value)
min: field.row.Buy_Rate__c, <---- the field to enter min Value
max: field.row.Sell_Rate__c, <— the field to enter max value
step: 0.001, <-----increments
