The first thing that comes to mind is thicker spring pads.
That is probably the cheapest way to raise your car, although it may only be by about a cm or two.
You might also be able to go with 80 series tires, but you would have to make sure they don't rub anywhere, plus your handling would suffer a bit. But then again, it doesn't sound like you will be driving on a paved highway either.
...that's all I can think of, that's quick and cheap.
"...rationality of thought imposes a limit on a person's concept of his relation to the cosmos." -Nash
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09 Jetta TDI