Because the incidental costs of acquiring capital from any source are going to be expensed into your transactions and paid by a tenant or buyer anyway, and with access to capital that I can get funded to you in 4-10 days or less, with virtually no headaches or personal qualifying restrictions (credit scores, DTI, number of properties already financed etc.) you can acquire many more properties per year. 

My credit score is 640ish on Experian but higher on the other two with a score of 700+.

Have a 750 plus credit score and 25% down and a LOI for 1/4 th of the purchase cost from a large development company.  

We begin negotiations again with a proposal for credit/remediation, but before that - let's check the score again, shall we?

The client stated house have close to $25,000 worth of repairs because the roof is no good and have a lot of other issues. the client want to know if i can purchase the property and sell it to her after a couple year once her credit score and income are OK.

I only ask to have a better idea of what I can do if I am unable to get traditional financing, I am currently working on my credit score and it is coming up, just slowly. 

HML have a place for when other options are not available because of restrictions, qualifications, credit scores (HMLs tend to led based on the deal/collateral, less on the credit score), time constraints, etc.  

I've got an income of 66K, credit score 680 and a student loan payment 500/mnth.  

We have cash, lucky us, great credit scores, but don't want to tie it up so may need look for investors. 

You are correct, it is toxic and will never go for par, though with a good borrower, with a high credit score, and payment history, low debt to income ration, are a part of a higher resale value.