dakar costs - from experience
I just got back from Dakar 2013, where I was racing a 4x4 car. We had an engine failure on stage 2. Last year I finished 39th in the car class with my co-driver, Patrick Beaule. This year Pat is entered on a bike and is currently running 63rd. I am one of his sponsors and he has shared the details of his budget with me. I'd like to try to help provide you some info. I'll focus on Pat's effort since your interest is to do it on a bike.
Patrick is a former cdn off-road (enduro) champ and is a strong rider. I would call him a AA vet at this point. He's an excellent mechanic and a very organized professional guy. I mention all this to give context to what is to follow.
The cheapest way to do Dakar is to sign up with Malles Moto, which means they carry your personal gear in a metal trunk and the carry fluids and large tools for the riders to use. These are the true privateers - they do their own maint. and less than 30% of them finish. Not counting the bike itself, these guys are spending $40-60K to do the Dakar.
The next step up is to join a rally team (assistance team) and share 1 mechanic between 2 riders. For those who just want to finish, this is a good option and relatively good value for money. The advantage of the rally team (e.g. Rallyraid UK, Memo tours, Desert Rose - those are the principal english speaking companies) is that they'll carry a bit more stuff for you, they'll take good care of you (set up tent, provide shade, cold water, little things) and you'll have a few other mechanics/riders to lean on for help. This option would be 60-85K not counting the bike (my pricing includes flights, hotel before and after event, etc.)
Patrick took the rally team approach but added a bit of cost by doing a few things differently:
1. He has one dedicated mechanic for himself. Having seen how his Dakar has gone so far, this was a great call
2. He brought two extra trunks of spare parts just for his own use. He has absolutely everything you can think of, except a spare engine (his plan was to do the event on one engine, but he was forced to replace it on day 5).
Not including the cost of the bike, Pat's total expense using this approach will end up being $100-110K.
Now let's talk about the bike choice. Pat's riding a 450RR and he believes strongly that it's worth every penny of the $45K it costs. It is so well built and such a common choice that it opens up options if you're missing parts or need help. If you're a master builder, you could start with a 450 EXC but I really believe the RR is worth it. I have ridden it and it is awesome. When the rally is over, you'd have no trouble selling it for 30K. Problem is trying to get one from KTM!
I understand your perspective of wanting to do it with your own support team - I am the same type of guy. The reality is that one seat in an assistance vehicle is $15K - that is the ASO cost plus any reasonable amount of expenses pre and post rally. If that person also gets paid, you're looking at $20K very quickly. To truly be solo, your minimum team would be a driver and a mechanic. The driver can help set up camp each night and the mechanic can sleep on the road. If you could afford it, go with a 2nd mechanic who could also help with personal stuff - riding gear, camelback, road-book, food prep (going to the bivouac cafeteria is a waste of time at breakfast when you need to leave at 4.30 AM) and parts inventory. These three could ride in an HD pick-up and you'd be in great shape. Problem is you'd be at $45-75K just for the crew and you still need to get the HD pick-up to SA.
ASO do an amazing job blasting through customs with their ro-ro boat from Le Havre. Anyone from NA always gets screwed at customs because you end up being a real exception and you'll be dealing with customs solo - a very very stressful experience and if you pad time for it, you'll have less time for testing and prep before shipping.
I think the ideal scenario is to join a rally team but to bring 2 of your own guys. There's no need to reinvent the wheel. There is so much hardware in europe already set up to do the rally. Why build your own and go through all the admin and hassle? The rally teams have generators, welders, tons of space, trucks that already pass the ASO rules, and they have dedicated drivers so you don't waste money on that seat. SIgn up with a rally team but tell them you want xx metal trunks and 2 seats in the assistance vehicles. Specify what heavy tools you want them to provide - if they don't have them, spend your budget on that. Buy a KTM (or Husky or Honda) parts card so you can use their on-rally assistance, but spend budget on your own parts (they're cheaper from home than on the rally and you'll save time and stress getting them at the Biv - which is a 2-3 square mile space by the way).
I think this approach would cost you approx $130K, leaving you 45K for a killer bike and $25K for testing and a "pre-race" (something to build up your resume and experience) to round out your $200K number. It's easy to spend money fast on the Dakar!
I hope that helps.