It would cost another $15k in foundation and utility hookup costs plus another $5k-$10k in marketing and sales commissions.

"I figure if I work with the listing agent directly, they're more likely to disclose the price I need to hit to win, and even if I come in slightly lower, they can still get a much higher commission by dual agency, as opposed to having to split the commission with the buyer agent."

For example, you close a deal with a $10K commission check and pay a 30% referral fee or $3,000.

Do they typically want a commission or portion of the rent?

You cannot go from W2 to commission, or commission to W2, and have 6 months at 1 and 6 months at the other..

He got a commission when we bought and sold.

So they can earn commissions, but can't actively participate, only earning referral fees. 

It's illegal in the state of Maryland for a licensee to wholesale per the Maryland Real Estate Commission 

Running the numbers includes calculating the ARV, and estimating the following: rehab costs, closing costs (I use 10% of ARV, that will cover a buyers and sellers commission at 3% each and 2% closing costs on each of the buy and sale), funding costs, staging costs, insurance cost, property taxes while you own it, utilities while you own it  Other tips:Stage every house you flip unless we get back to a stupid market like we had two years ago where you got 20 offers on the first weekend at $50k over ask with no inspection contingencies.

Closing costs on the front end, a second agents commission on the back end with closing costs on the back end might be another 10k-15k.