I don't have money to buy v.ray for blender.... is there any affordable animation plugin in sketchup that is compatible with v-ray?

Check this tutorial: How to Create REALISTIC Materials | Vray 3.4 for Sketchup

You could also try a program called Sculptris http://pixologic.com/sculptris/ It's a separate program from SketchUp, and only exports in OBJ format, but if you get TIG's OBJ Importer, you can bring whatever you sculpt there over to SU, provided you don't make it too high poly. I recently sculpted a rock formation that a structure was supposed to sit on and was very surprised I was able to bring it over to SU because it was higher poly then I thought would work. Also, if you have problems importing using OBJ, you can try using Blender to convert the OBJs to DAE, which sometimes works better for certain models.

Can you post a screen grab of what you were able to achieve and we can help from there.

Great job of modeling HornOxx