I just had a furnace put in a one bedroom, and that cost me around $2000 installed with all new duct work throughout, but it was a buddy who did it...

I have learned how to install P-traps, how to wire breaker boxes, and how to re-run ductwork. 

The inspectors kept failing me because the old stuff didn't mesh well with the new stuff So I replaced all duct work.

@Mike WallaceI imagine all the duct work is already in.

Brush up on building code requirements: in basements you're looking for egress windows that are 5.7 sq feet or more openable (3ft by 3ft casement style windows work best), and ceiling heights 6ft 8 inches or greater (as little as 6 ft 4 inches is ok under ductwork and beams though)3.

Clogged filters, leaking ductwork, blocked vents can make air work harder.

I am impressed you are getting 7 furnaces, duct work, line sets and building soffits for $8500.00.

The rules for the gift will depend on the loan you are getting.The other option would be to partner with someone that will split profits in exchange for the down payment contribution.If you are really talking about true cosmetic issues (paint and minor updating), then you might be able to get a conventional loan.However, if this is a flood damaged home, that will most likely not happen.Flood damaged properties have several things to consider:If the house was flooded (versus wind damage to roof or exterior siding), there is a high risk of mold damage, electrical damage, HVAC damage, HVAC duct work mold issues, and hidden surprises depending on the level of flooding.On a related note, if it's in a FEMA flood zone, it will require flood insurance.

It also has to do with how the ductwork is laid out short runs vs long runs. 

Same is with the remodeling - I estimate that more than 25% of our rehab cost typically is spent on things inside the walls - new water lines, new sewer pipes, new electrical, sometimes corrections in messed up ductwork.