I usually get my engineering structural calculations from this outfit. 

$120k seems cheap to fully build and outfit 5 "brand new" apartments.  

So, if you are serious and have some experience, you can probably cut a few years off your business development trajectory, and save more than the $15-$20K fee by retaining this outfit.

Keep in mind as you run your numbers that you will need a budget for any renovations and to completely outfit the house as a STR.

The houses are usually controlled by the wholesale outfits who have become very greedy and anything found on the MLS will not work numbers wise. 

Quality of work has also gone down hill substantially over the years and it can be a risk to try out any new outfit.. so not to sound arrogant but we are our own skilled labor.

There's big box like Lowe's and Home Depot and they have builder discounts but you need to buy in bulk, there' smaller outfits for lumber and sheetrock and of course paint too.But there are lenders who will deal with you if you have good credit and liquidity,

@Jay HinrichsI spoke with my PM in Jackson, who is a smallish local real estate management and sales outfit , located in South Jackson. 

@Christopher Morris -- I have a two-family in North Jersey outfitted entirely with ductless AC/heat.

Rural 1st is a national outfit with a good reputation and they might be able to assist with the land purchase.