How do you factor holding costs wholesaling deals

[Account Closed]

Im looking to use this formula to calculate my offers on deals to cash buyers who fix and flip. It was suggested that I calculate fixed costs at 15% of the ARV, and the end buyers profit at 30% of the ARV. Is this reasonable? My formula for calculating offers would then be

100K x.30 = (30K Buyers Profit)

100K ARV x.15= (15K Holding costs and fees)

10K-(Repairs)

5 K- (Assignment fee)

100K(ARV)-30K(buyers profit)-15K(Holding Cost)-10K(Repair Cost)-5k(assignment)=40K

Is the 15 percent holding cost eating up too much of the profit or is this realistic?