I went to sign up this morning, and it costs an additional $100. 

Ask your broker if the brokerage has a referral division and if there are any costs.

This post has nothing to do with cost segs.

For flips, ensure the profit margin after all costs is at least 20%-25%.

You will incur more lending costs but you will only be in the first loan for 6 months.

Just factor the cost into the rent.

Selling and buying something else you want keep and doing a cost seg in would help with the tax burden probably better in this situation.

Kudos to you for doing something to create a secondary income stream. there are 5 income streams in RE rentals, possibly six if you do things a certain way.The reality here is your model (buy box) is suffering from too high an entry and too high a cost of capital.

After closing costs, it was about $107K.

You have to have exit values of single family homes high enough where build cost can work.