Right now the only AF option for macro with the GH1 is the leica 45mm lens, but that is not a budget lens.
If you want simple and can give up on AF you can get the oly 35mm 3.5 with the panasonic adapter, you will still be able to set aperture with the gh1. So you can see the shot without it getting darker when you stop down. I pick up a used lens for 147 on ebay and a 100 dollar panny adapter on ebay for my epl-1 and it is quite a nice marco set up. Here are some samples of the lens.
I you want full manual, the canon fd 50mm was a good macro lens if you get an fd adapter.
Super Frequent Flyer, no joke. Ex Patriot and loving it.
Canon Eos 60D, T1i/500D, Eos1, Eos 630, Olympus EPL-1, and a part time Pentax K-X shooter.