Good luck. I think you'll do well.
There's a concept in finance, Time Value of Money, and with interest rates at Very Low, people are willing to wait a month for you to work out your financing if there's a significant difference in their carry-away money.
Also, the dirty little secret about the cash buyer? They can afford to walk and leave their earnest money behind. The 3.5% down buyer? Not so much.
Highest and best offer could be seen as $125k cash or $150k mortgage depending on the seller. Often I keep reading that foreclosures sell to cash at lower offers than was made with financing. But a real seller who wants the highest amount may or may not take a lower cash offer. They may decide to accept a larger mortgage based offer hoping to net more money when (if) the financing comes through.
Look at it from another perspective. If you were trying to sell your house, and wanted to sell it quickly would you rather take a lower cash offer that WOULD close or risk taking a higher offer based on financing that might not happen? In essense that is the choice many sellers are making. Take a sure thing at a lower price or something that would give you more money but might not work after working on it for a month or more. Some will take the lower cash offer to be safe and sell. Others would take the financing praying they made the correct decision.