Hello,
I'd like to suggest Sketchup as your modeling program; the free version does everything you could possibly want and I believe it is the most intuitive and easily learned 3d modeling software available. Also, for just viewing Sketchup models a free viewer is available. There are thousands of free models available - most manufacturers of kithen appliance, bathroom fittings etc are downloadable from manufacturers' websites. Have a look at the "SketchupVideo" channel on YouTube - many tutorials and other useful information; take a look at Nick Sonder's work. Also, there are excellent free rendering programs if you want to create photorealistic renderings of Sketchup models.
I could model your complete house, plus your different alternative designs and a couple of revisions for £150 on the basis that altogether this would represent about 12 hour of work. I would also be prepared to answer any questions about using Sketchup to guide you as you go through the learning curve - this would be included in the price.I should add that I am very experienced in Sketchup and this job would be very straightforward for me.
Regards,
Stu McCabe (Plymouth, England).