Is there any way to upgrade directly from VirtueMart version 1 to 3 other than the two step process of upgrading VM1 to VM2 and VM2 to VM3? I am using Joomla version 3.3.6.
I have quite a few VM1.1->VM2.9.x using the standard VM migrator - (i.e copying the VM1.1 tables to the J3 DB and running the migrator)
assume VM3 will work as well..
I your case I would recommend to migrate but not upgrade. It means, firstly you will have to install a fresh VirtueMart 3.x and then migrate all data from 1.x to 3.x. As far as I know cart2cart does such migration (not affiliated with them, probably there are other services, just google). In such situation you will perform only one step and what is important your 1.x store will be live during migration. The thing is template will not be migrated, so you will have to take care about design after migration is completed.
You can go straight from VM1.1 to VM3 if you wish, but is easier using this migrator extension : http://extensions.virtuemart.net/import-export/virtuemart-migrator-detail