My view:
Your offer of 140k versus a 155k LP.
Call it 155k to see if numbers even work on the higher end.
50k rehab cost, add 10% reserve minimal= 55k
You're now in at 210k
List it at 245k and say it sells for that
= 35k Gross Profit
- 6% commission ($14,700)
- ±2% closing cost ($4,900)
= ±$15,400 Net
15,400/210,000 = 7.3% return.
I know I am missing several operations and fee items, but that's unique to each individual.
This can be viewed as a terrible return by some people, but if you do 4-5 of these a year, it starts to replace your income. On a 50k rehab, I have never ran into it holding a house longer than 2-3 months. I understand you want to be conservative and say 6 months, but as long as your stay on top of your contractor and he completes work to an agreed deadline (which I hope isn't spread across half a year, any GC that will be spending half a year on a 50k job, is more than likely running a dozen+ other jobs meaning less attention on yours). Most GCs want to get in and get out quick. More time = more money and doesn't always mean better quality. There's a balance.