Target ROI and % of costs on Flips

[Luis Lopez]

I'm a new wholesaler in Miami, FL who's in the process of putting together a spreadsheet to help me analyze my leads and make my offers based on what my potential buyer sees. In other words, I'm digging in deeper than the 70% ARV rule by looking at my numbers starting from the back end to ensure my buyer makes their targeted ROI and anything in the middle, if any, would be mine (which would be adjusted accordingly throughout my negotiation with the seller).

Where I need help from seasoned investors (local preferable but not necessary) is plugging in the basic variables using rule of thumbs.  I say rule of thumbs for now because, through further studying and experience, I expect to improve the accuracy as I go.  But I would like some help getting this up. 

If anyone can assist me with a real basic/general %  for each of the following, I'd really appreciate it.  I've already begun plugging in based on the numbers on the transaction for my own house but thought I'd reach out to the community anyway.

• Target ROI on a flip (minimum, average, and realistically preferred)
• Purchase Costs (% of Acquisition price aka my price)
• Holding Costs (per month or year, whichever)
  • Average holding period(s)
• Selling Costs (% of retail price, my buyer's price to the market)

I totally understand the numbers can be extremely high or low depending on location and the individual deal itself but I'm just looking for your typical deals and their averages so to give me an idea of what to look for.

I'll apologize in advance if anything above isn't all that clear. I'm trying hard to get the REI lingo right. I'll be happy to clarify or expand if needed.

Thanks,

Luis L.