I've been looking at land investing for a while and am finally saving up money to get started. 

It's key to chat with local money-wise folks and house bosses for tips.

Money is getting tight, thinking about getting a personal loan to buy me some time. 

Purchase price: $18,000 Cash invested: $245,000 Sale price: $335,000 New Consruction spec home built with the help of a hard money loan from Upright (Fund that Flip at the time). 1420 sqft, 3 bedroom, 2 bath home on 1.8 acres.

That amount gets deposited into my bank account (net amount).So my confusion is when I reconcile my business bank account the only money shown is the net rent amount.

THAT is awesome diversification, and diversification (to me) is more important than the extra money that active MF investors may or may not make.

Though it may seem to save them money, many homeowners end up with shoddy work being done that isn't to code, and end up paying a fortune to get it corrected.  

What's the formula to determining how much money we are able to borrow?

They had trouble renting a commercial space for me and we held money in escrow which was refunded to me to my satisfaction.

Your thought process on the contractor providing quotes to possibly "win" a job may seem correct on surface level as a lot of businesses offer "free-mium" products - but ultimately time is money, especially in real estate where good contractors are in high demand and could better spend their time finishing a project before accepting the next one.