Dont be so concerned just with the "offset" because it can change with the width of the wheel.

Just make sure the backspacing is similar to yours, more reliable way of checking that its gonna clear the suspension.

Offset for eseries is +6mm, but i had +11mm alloys fitted to my car without dramas because the backspacing ensured it cleared the suspension

Also just as important, check that the centre hub hole in the wheel is gonna be a perfect fit for the hub on the car

http://www.performancewheels.com.au/technical.asp

you could also get addapters & get them certified ? not sure on cost.
then fit whatever you like ..?

also spingwood tyre & wheel .(sevice rd along from ikea) has some pre au

dave .