Well, it depends on what you want. SourKraut's is good, but he does have some stock issues. If you're looking for resin parts there's Dave at American Industrial Truck Models. If it decals you need, then I recommend you get in touch with Jerry over at Model Truckin'.
Another place is Model Trucks & Parts. Check out the Czech Truck Modell section!
I can also recommend Evan over at Melbourne Model Truck Accessories. Another guy "down under" is Bruce at GR Decals. He has a lot of the Kangaroo P/E.
There's also Sharon at Spaulding Trading & Shipping. And there's Special Appearance Decals.
If I remember any more, I'll besure to post them.