Aarron,
To be successful at wholesaling, what you need to do is find good deals (really good deals) AND pass them on to your buyer.
To do that, you have to have a very good understanding of your market. My suggestion is to go look at a minimum of 100 properties for sale in your target market and see what is selling for what. Review your market's average DOM (yes thru a realtor). Learn the market.
As to your numbers, you need to know your realistic selling price, not max. That is what MOST new wholesalers try to do and all it will get you is frustration. If the MAX selling price is $100K (highest possible) do you think that it will really sell for that in 4 months or less? Doubtful. Much better to give a realistic selling price of $90K and base your numbers off of that.
An overestimated cost of repairs is all you really need to have available. As you said, every investor is different, and it's not your concern about their holding costs, resell costs (and it costs much more than 5% to sell), etc. What you need to know is what is their MAX purchase price based on resell value AND be LESS (the more the better) than that.
Raj