Well firstly, good luck to you! Professional LRP is hard to turn a profit on and still keep a high quality - you may find that you have to taylor it to the lowest common denominator (hitty-hitty) crowd in order to turn a profit.

There are several professional LRP companies here in the UK (and in the US too I hear) but they almost all suffer from the above problem. And all rely incredibly heavily on voluntary workers, in both the roleplay AND office / admin sides.

Many reward OOC volunteer work with IC bonuses - tough NPC characters etc. I humbly suggest that you steer as clear of this as you can. Not only does it blur the lines between the in and out of character organisation / hierachies, but this kind of reward will always attract the type of people who would abuse it. When these people are effectively your 'customer facing staff' you have to be very careful that they present the kind of impression you'd like to leave your players with.

For more specific info, your best bet is to post on www.pagga.com in one of the game creator's forums. There should be quite a few people there who run pro/semi-pro games.