For example if you promise the seller a fixed price and then later on house sells for less than expected then your profits will be marginal or you may end up losing money.Meanwhile if you can sell it for a much greater amount than expected , seller might want to take a cut of your profit beyound what was agreed upon.How did you go about this ?

I would remove the cabinets and sink in that little room, add shelving and some drawers, and put a cute door with a frosted window on it and create a new pantry out of that space.

The best you can do with your friend is tag him along for 4-5 deals from start / after acquisition until sold, to mitigate the pre-acquisition phase, he can bring you the deals, you vet it, then you take a cut for being a backup solution provider, say 25% of net profit, the role might involve time to vet and visit projects until sold.

we do very little at the big box's we buy all ours from supply houses.. and or our subs buy the materials we rarely acutally buy anything. 

There are companies that ill help you negotiate with insurance companies, but they take a cut off the top, up to 30%. 

I'm not sure where this idea is coming from, maybe it is the show Shark Tank itself, but I've seen a lot of posts recently where people ask where to find investors to fund them buying a house off of MLS in exchange for a cut of the profits. 

That the only tool that I found that added that much genuine value was SmartBnb, and they dont want a cut of my business. 

A bit late to the party here, but I would second the folks that said use a cut-in brush instead of tape.  

I think so many landlords just keep a lawn mower at their building and then just say "Hey George, go cut the grass for me and I'll pay you $10 a cut."  

Now someone suggested that I can just sell the house myself directly to an investor without having the realtor involved as the middleman so that I don't have to give them a cut and I can keep more of the profits.