SOulds like the sellers agent did a poor job. 

Using comparable sold properties with similar condition to your end product, within a 1/2 mile (sometimes a little further), less than 6 months old, within 20% of square footage, not crossing major boundaries ( high ways, school districts, city lines, etc).

Generally the conventional, non FHA loans have been cheaper and preferred and FHA was a backup for those that could not otherwise qualify for those loan products.  

I realized I wanted to get into real estate 3 years ago after I had read Rich Dad Poor Dad on one of my field ops in the marine corps.

Welcome to BP community, hope all is well.What was my driving force was eating up audio books to speed up the gaining knowledge process, in return I would gather my questions faster for more deeper research.also all podcast/video-blogs from BP, listen to all of them until you start feeling a craving for a certain niche, then focus more on that new found hunger.recommended books:-Profit First-10x Rule-Ultimate Beginner's Guide to Real Estate Investing (free from BP)-Rich Dad Poor Dad-Millionaire Real Estate Agent (known as the Red book within REA's)-Millionaire Real Estate Investor (known as the Blue book within REA's)-4 hour work week-The E Myth for Real Estate InvestorsGood luck, you seek , you will find#keepthehustle #lifeisworthliving #notdreamingitsreality

So I was wondering if there are any particular things you can do to make the product irresistible to buyers.

Cash flow is required by poor investors or those that are poor.  

HELOCs are typically bank products, not mortgage company products, so they have a lot more leeway in how they underwrite them. i.e. they are not trying to meet some government organization's criteria, just their own.

I have poor credit,  I have up to 30,000 to invest.

How are you getting 5.125% fixed for 30 years on a commercial product?