I made a mock-up of several laminated panels from 7/16" OSB board and 1" rigid insulation panels, glueing the OSB to each side of the insulation and creating a staggered edge that provides additional support and reistance to wind and rain. The strong laminated panel offers security, protection from heat, cold and wind, and ease of installation. By fastening the panels along the support structure, the panels act as rigid diaphrams, able to resist wind and earthquake lateral and twisting loads.
Doors and windows can be cut into the panels to suit local preferences, or pre-determined by incorporating blocking within the panels for future cut-out (dash lines would indicate where to cut). The openings can be based on off-the-shelf pre-hung doors or windows, or simply be a cut opening finished with local window or door materials.
The structural system is based on the universal 4ftx8ft module (to allow roof overhang), however, I show a longer composite I beam system for framing a 4 quad building that can be for individual houses or variations such as the 3 room family house with a covered courtyard. Note that the I beams "A", "C", "D" continue the walls up from below in order to provide privacy between rooms. The primary posts P1 are supplemented with other posts which provide framing support to the walls.
The foundation can be any system. I have shown a simple stone base contained by wood edging (isolated from soil contact), and a plastic sheet provides a moisture barrier below the insulated floor panel. Three foot long hooked spikes driven into the ground along the edging provides lateral support to edging and anchoring to the entire structure.
OSB panels are painted for moisture protection, and the roof rain screen panels could be a sacrificial painted OSB (corrugated metal panel would be better). Any water that passes through the fastening penetrations is stopped by thte plastic sheet.
The costs exceed the $300 goal when doors and windows are included, however, creating a 4 quad building starts to economize, and producing on a larger scale should bring costs down even further.

·         Customers struggle just to survive, so the burden of extensive labour may be the last thing they want or are capable of- my designs (The Modest Module,  and The Panel House) use  established technology, material and simple assembly processes to reduce the labour component.

·         Their varied life styles need a responsive house assembly that accommodates personal input �my design allows for the modular panels to be cut anywhere for windows, doors , vents, and to be able to temporarily remove interior wall panels to suit changing needs.

·         Security,  protection from the weather, a non toxic environment and comfort are basic desires by all humans- my design uses one modular panel system for roof, wall and floor to achieve these goals.

·         The progressive assembly process is designed to be fast and simple. Although not particularly innovative, it is responsive to potentially uninformed customers.

·         The costs to produce the stand-alone single house is in the range of $500, but with a 4 quad house the price starts to come down. Like most proposals, I have not included the cost for off-the-shelf window ($180) and pre-hung insulated metal door ($220). My design does have the attribute to use the cut-out panel portion as the actual door (edge trim would be required) and window shutter, which would help reduce costs.