@Leilah Davis I think the reason you dont see alot of small mom and pop new home developers is two fold, 1) amount of capital required and 2) its alot of work to GC your own new build. I will elaborate.
On the capital side, unlike your scenario, most people done have $150-300k sitting around for new construction funds. This means that you need to borrow the money, typically in the form of a new construction loan. But those that offer new construction loans, typically require alot of capital (~25% of total costs) and experience. They banks or lenders find that type of loans crazy risky and if you have zero experience, they will be very unlikely to give you a loan. The duration of a new construction build is also much longer than a rehab. My builds take anywhere from 5-8 months after ground breaking. Thats a long time to have your capital tied up in one project.
On the work side, to do new construction requires tons of pre-work needed just to get to the point that you can start construction. This included finding the build lot, developing a rough idea of the what to build (size, beds/bath count, finishes, etc), running comps to determine the area can support new construction, checking zoning and city requirements, etc. Once you have found the right lot, you then need to secure it (purchase or put it under contract) and start the house design process. The design process could be purchasing house plans online or working with an architect or house designer. Just that process can be a ton of work. This is all before you can even start construction.
Once you have the building lot and building plans set, you can start planning on construction. This includes getting bids from general contractors/builder (if you live in an area where none licenced people can not act as GC for there own new construction bids) or get bids from subcontractors. On a rehab, the contractors/subcontractors can walk thru the house and take measurements and see what they are bidding, on new construction, they only have a set of building plans. Alot of good contractors just can't understand how of bid new construction (I think they struggle to understand building plans). I have had a vinyl siding contractor tell me that he would not bid a new construction job until after the house was framed and sheathed after providing the building plans to him.
Additionally, just because there is not surprises with the build, there is still plenty of ways to go over budget on a new construction project. Allowances in build contracts is one that can really drive the costs up. If you dont do a good job in the planning/bidding phase, you can easily miss or under estimate allowance items. For example, lets say that you originally plan for some basic flooring and put in a material allowance of $3/ft2 for flooring and the house has 1,500ft2 of flooring required. After you start construction, you decide that the market requires hardwood flooring for your build to stay competitive and now the costs are in the $10/ft2 range, which means that you just added $10,500 to your build (over the allowance). There is also the potential for change orders, once the build starts and you realize that the build plans aren't what you wanted or something just needs to change.
Now for some specific's of your proposed build. In New Orleans, you would will be able to act as your own GC of this build. All new construction must have a General Contractor pull the building permit. This will mean that your going to have to include the GC costs in your build (assuming that your husband is not a licensed GC able to pull permits in the city). Also, there are lots of areas in the city that can NOT support new construction pricing. Prices have been increasing quite fast and alot of contractors are very busy right now. In our city, its hard to keep costs (land + build) under $100/ft2, so in order for the deal to work, comps need to be north of $125/ft2, which is not everywhere. In the area's where the comps are high, the land costs are also high, which often makes the deal not work.
You did not mention what your budget was, but I assume its in the $150-200k range for a smaller 3/2 house. Assuming that you have included all of your costs (land+build+holding+sale) in your numbers, $30-40K is not a screaming deal, but may be do able.