There are a bunch of Stug F's on eBay but all are from China. Prices around $17.00 USD with postage. Not bad prices if you just have to have the kit. Here is a list.
I have purchase a lot of kits from China. Just pick a seller with 1000+ positive feedbacks and you should be good. My worst transaction from China is better than some of my USA purchases! And it was not the seller's fault. One package must have set in the rain for two days! The kit was shrink wrapped so only the shipping box got was ruined.
I'd give it a try. Does take several weeks at times for deliveries.
Also a lot from Germany, but they cost more.