I'm really not knowledgable about the various vendor systems available. But here are some questions that come to my mind.
When we refer to "our vendors", it seems like we are concerned with vendors for two possible different purposes:
(1) Vendors which sell goods and services totally on behalf of the city itself, and
(2) Vendors which citizens use to sell their own goods and services, which the city mandates in order to serve the purposes of the city.
It seems there are few if any vendors falling into the first catagory, except perhaps the machines in the casino, which I guess you would not call vendors (?). To my knowledge, they are the only ones which provide their entire profit to the city.
All other vendors would be for the purpose of selling the goods and services of private citizens. The purpose of the city which they serve is the collection of sales tax. There may be other useful purposes which they might serve, but at this point we haven't defined them.
The idea that the city would collect sales tax is an original idea in the creation of Neualtenburg, and I have certainly supported it as a fair means to provide income for the city. But, perhaps, before we focus on alternate vendors of vendors, we might consider the sales tax issue entirely.
Sales tax was proposed as a primary revenue source in the Phase One Neualtenburg. However, as we moved into Phase Two, we realized that we were going to have to collect land fees in order to support the private sim, which was never originally envisioned in the original charters. Since land fees are a natural form of revenue generating in SL, it has been a reasonable shift.
At the same time, for various reasons, sales tax has generated an incredibly tiny amount of revenue; less than 1300 L since Jan 1, and perhaps 4000 L in 2004. Of course, there are various factors which have led to this, and some of those factors might change.
But, we may wish to suspend sales tax for the time being. Adding to the fact that it has brought in almost no money, the lifting of it might encourage more commerce, and more traffic to neualtenburg; ultimately it may raise the desireability and value of the land itself.
Also, removing the sales tax rationale removes the need for the city to be involved in the problem of vendors at all. Simply one less knotty issue to deal with.
And, well, I did say that I have supported sales tax as a fair and reasonable system for generating revenues for the city. When I say that, I am speaking only about the situation in SL. In RL, I am adamantly opposed to the sales tax. It is a cop-out tax imposed by politicians who have seen it easier to create a regressive tax affecting the lower classes of society far more than the richer classes, AND, at the same time, repressing street-level commerce in favor of large scale enterprise which is far less affected by it.
Please forgive my rant, especially since it applies very little to SL commerce. In SL, essentially all transactions that would be affected by the sales tax are what are reffered to as "disgressionary" purchases, things which you buy not because you need them to support life, but rather because you'd kind of like to own them. Sales tax is much more appropriate to that sort of purchase.

Sudane