Hi Chetan,

Thank you for your message.

As it goes for having different pricing for different users you can use our build Discount levels -> http://devnet.kentico.com/docs/ecommerceguide/index.html?discount_levels.htm
This basically means that you can assign user to given roles and these roles will have some discount for your products.

As it goes for the bulk buyout the easiest solution would be to create a new product which would already contain 5 units of given product and you would assign a different price for this. You can then easily set some department to these "bulk" products and show those departmens only for some special user roles -> in your case dealers.

Let us know if you have further questions.

Kind regards,
Richard Sustek