Migration joomla 1.5 a 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 profesional and longlasting collaboration.
thanks