Migration joomla 1.5 to 3 (joomla + virtuemart)

I have several clients who are still using Joomla 1.5 , we should migrate them to 3.0 version
this project refers to a joomla site 1.5.26 + virtuemart ( wich has about 500 products )

After we will be done with this one there will be much more to do, but without virtuemart.
I hope I can count on a professional and longlasting collaboration.
thanks