when wholesaling properties do the wholesalers include the estimated holding cost into the repair cost or would the holding cost be added on top of the repair costs by the investor?
Holding costs are added to the repair costs. Holding costs vary widely depending on what you plan on pricing the house (the lower the margin, the faster it will sell) , whether you’re renting it or flipping it, what time of year it is etc.
Repair costs for the same house should be the same regardless of your exit strategy (one caveat - keeping to rent will yield a different repair costs) for the most part.