You can use the files in different 3d editing programmes, architect or home design programmes, which can import 3ds files, or if not you can convert it into the adequate file format with other converting programmes.
Think it over, you can purchase 402 3ds files at other website for $5.00 USD on average, thus these 402 files would cost $2010.00 USD. We both know, that you will not need all 402 files at once. However if you have more projects, and you continuously pursue designing work on the computer, it is very advantageous, if more 3D models are immediately available. The more and varied 3d models enhance your effectiveness, and you can service your clients with more varied design plans of different style. Therefore it is evitable that you will use all files in some time.