In many ways I find it easier to just use Zierer. They are not the cheapest but it is no hassle with them. If sponsorship letters are required it is all taken care of for you as they co-ordinate with Radisson. I usually use them for my own visas just because it is easy and fast.

There are many visa services and you can go straight to the Consulates as well IF you live in a city that has one locally. It all depends on how much time you want to spend getting your visa and messing with it.

The one thing that I did see that was ridiculous was the fees Zierer charged for getting extra passport pages etc. You can just as easily go directly to the passport office and get this done for almost nothing.

We went straight to a Chinese Consulate once for a group trip we had on Residensea. Amazingly there were different forms and requirements depending on what STATE you have residency in the US. It was a real mess. We had people from all over the US.

That is when we found FLYCHINA for the next group.

If it is a Radisson cruise though I would still use Zierer. If anything goes wrong at least you have the "official" visa service that RSSC recommends and that helps with complications if anything should happen.