Might be too late to provide some of the information -- nevertheless, here is an update.
I charted with a company called VPM or Bestsail. Bestsail AG
I was a little nervous about the company because I didn't get a whole lot of information in the booking process. They basically just wanted to make sure I was paid up. In the end it worked out fine though. The price was comparable to the other companies and there was indeed a boat ready for us when we got there. The charter company is located in Anse Marcel, which is the bay just east of Grand Case.
Customs was a bit of a pain but not to bad. We immediately cleared out at Anse Marcel. That cost 2.75 usd. We then went down and stayed in Simpson Bay one night (and took part in the Heiniken Regatta party) and then spent the next day in Simpson Bay Lagoon. We didn't clear into the Dutch side (were too late to make it to customs.) I don't think anyone really cares or notices.
We then headed over to Isle Forche (on St. Barts) and spent the night there. The next day we went down to Columbia beech on St. Barts and then spent the night in Gustavia. We paid 15 euros in Gustavia just to anchor for the night and to clear in and out. We were able to clear in and out in a single transaction. Again, technically, we probably should have told them that we had spent the previous night in St. Barts.
We then sailed up to the north side of Anguilla. We were to late to make it to customs there so we never cleared in or out of Anguilla. It does sound like Anguilla charges some hefty fees for national parks, etc. I think one night would have been around $60 us. I don't know that for sure...
It was a good trip all and all. Lots of wind. It was more out of the north, which I understand is a little unusual for down there. The anchorage in Anguilla (Road Bay) was rather rolly and uncomfortable for example.