RTW solo, S America or SE Asia first, plus costs.

have you looked over the gap year branch?

Your plan to me looks fantastic you don't have a plan. Thats the way to go you are your own captain not tied down to a time tabel of 3 days in this town ect. you are ages ahead of many of the other posters here.

I would say your budget looks fine for the places you want to go and the style you are expecting. The flights may be $$$ that is the only thing i would look at to get an idea of costs. I am not going to suggest a route to take because I think you have a good idea just to let it happen. for example mex central america from panama by sea to colombia ecuador peru bolivia chile,you will need to be in a larger city to get flight to Asia Santiago?

yes very doable good luck!

Santiago or Buenos Aires would be the most likely places to fly to Asia. I think one airline does the Asia to Buenos AIres route. My guess would be you will most likely fly to Sydney/Auckland and connect onwards from there to a SE asia destination. You can get cheap flights through Tiger/jetstar/virgin to SE Asia from a few cities in Australia. Might be worth checking out.

10K isn't a bad budget. Especially for the areas. As Je55689 said, the flights will give your savings a financial hit for six. But travel in those parts is a lot cheaper than Europe/UK.

Asia is NOT dangerous!
India is meant to be the cheapest of all so I don't see why you shouldn't go there. South America is more expensive I believe. I think that you will be tempted to do more flights eventually, specially if you haven't been on a so-called bumpy bus ride before...

I'm heading round South East Asia on my own in October and will be doing what you plan to do by going with the flow. It's the best way to travel I think.

As above posters have said the bumpy bus rides will probably grate on you so flying might just be an option not to be ruled out. Obviously the price is a factor but you will be travelling in relative comfort.

One of my worst bus rides was an overnight Greyhound from San Diego to San Fran. Saved on a nights accomodation but sacraficed comfort and a nights sleep. It may be a cheaper option but it doesn't necessarily mean its the best.

This is the issue with night buses. Everyone raves that you save a nights accom and travel at the same time. But you always arrive feeling terrible and wanting to sleep for a few hours. If your ok with that, then do it.

I got to the backpackers before being able to check in so ended up falling asleep in reception and waking up with a dozen students staring at me like I was an animal in a zoo. Then when i checked in I went to bed, probably wasting a day of seeing San Francisco.

Happens too often Bearded one. It seems like a great move til you actually arrive in the next city feeling like trash.