doesn't anyone know about this?

I think I read that they do not offer one for a shorter time period. It's too bad. We are in the same boat, will only be driving through for 4 days, but will need to buy the 6 month pass.

For sure, you must have one and they are now checking at the borders and at random within the country. There is no shorter alternative, and the cost for getting caught without one is steep. I travel through Slovenia several times per week, and have seen that, as of this year, they are taking enforcement seriously.
There is no toll alternative, only the vignette.

Of course, the back roads might be lovely

Where do you BUY these stickers?? We are renting a car in Dubrovnik and will also drive thru some of Slovenia (4 days) before returning car to Zagreb.
Can we buy the Vignette at the rental agency in Drubrovnik?

I just found out: From 1st July you can buy 7 days vignette for 15euros and years vignette 95euros! And no more 6months vignettes! This doesn't help me since I will be there in June, but its good news to others.

We will be there in May 2009, so the 6 mo is all we can get. BUT, do you just buy then at the first toll entrance? when you cross the border, or when you pick up rental car in Dubrovnik?

ttt

You can get them just past the border entry - there will be signs for them. Or at any petrol station. I doubt if they are available at all outside of Slovenia, and certainly not Dubrovnik, as it is quite far away.
Thanks, humanone, for the update starting July 1. Seems that the year vignette will go up 25euros in price, though I'm sure many will be happy for the 7 day option.

You can get them on the borders or petrol stations. Yes from July we get 7 day vignette and yearly for 95 Euro. No more 6 months. But don't worry. when you travel around the country you will still pay less with vignette for 35 Euro then before with tolls. Vignette is good solutions, only short time visitors are worst off. If you rent a car in Slovenia a vignette will be included in car rental price.

So you don't pay tolls with the vignette, or do you still have to pay?

There are no tolls, only the vignette to pay.

I just drove thru Slovenia from Croatia. Rented a car from Dubrovnik and went into Slovenia to see what it was like. 35 euros cash only for vignette sticker at the highway booth.

I accidentally went thru the automatic booth the first time without paying attention without a sticker. On the way back out to Zagreb, I stopped at the booth and spoke with a lady about it. Had to pay. When crossing the border, the guards stopped me at and asked for my sticker. I showed it to him and he demanded that I put it on the windshield. Mention something about a 150 euro fine without one. Pretty stiff