Hi,
Another Suggestion is:
1) Create a Project with 100 WBS & each WBS will be treated as a Villa.
2) Create NWA for (Engineering & design, Land preparation and Construction etc.)
3) Assign materials to these NWA.
4) Assign Sales order to Each WBS for each villa order/cost.
5) Settle your actual cost of Project either to cost center or Final Asset.
Also lets wait for other expert's suggestions.
Regards
Shishir