There's a lot of migration tools out there. Not sure if you have budget constraints but generally you tend to get more out of a migration toolset than the time it takes to develop something in house to do the migration. There's a lot of migration solutions out there, from a lot of different vendors. Bamboo Solutions, Axceler, Metalogix, and MetaVis Technologies come to mind.
I don't think you'd have a lot of success with export/import, backup/restore, or raw DB migration simply because the versions are different. You need a tool that will translate WSS3/2007 to 2010. I believe the vast majority of migration toolsets (from companies like those listed above) have upgrade capability also. Many of them also offer trial periods to sample the software.