A lot of people use it inluding myself, so sketchfab is a great website to use not just as a market place but to show off your models to your clients.
I use it to send 3D Blender models to my clients so they can view and approve the models prior to editing images, doing this has been such a time saver as prior to this I was rendering images editing and sending to my clients only to be told days later they wanted something changed, below is an example of how you can embed a 3D model into your website.
With Sketchfab you can move, rotate and zoom into your models, I always export my models as an FBX file then import into SketchFab, you can actually get a plugin for Blender so it imports direct to SketchFab from Blender.
You can edit all sorts from materials (shown on the left) to lighting, you can even use HDR lighting for a better image. If you wanted to there is also effects you can add such as Depth of Field, Sharpness, Bloom, Vinette and so much more.
You can set this up so that only those with the link and see the model, so it’s private between you and your client.
You can even view your model through VR googles so your client get to feel they are actually in their building or if your a product developer your client can see their product first hand prior to manufacture.
So how much does this cost:
Free version you get to upload 10 models per month.
£22 ($24): 50 Uploads and private uploads.
£95 ($129): 200 Uploads, Unbranded Viewer, App Free AR, 10 Seats (so you can collaborate with your team).
Overall I would thoroughly recommend using Sketchfab whether it’s for selling your models or using so your client can view their models.