Suggest a best option for upgrading my wordpress.com blog

Hello all,

I have a blog on wordpress.com ( http://imdjkoch.wordpress.com/) where I wrote about Oracle Technologies. The blog hits 2,77,640 visits in 2 years and now a day’s getting 1000 visits a day. Now I want to join the Ad-sense club and go to a higher level of blogging. Since wordpress.com doesn’t allow Ad-sense program, I am thinking of upgrading my blog.

I have found three options.

1. Get a domain name from wordpress.com and apply for their advertising -WordAds (through Federated Media).
2. Get a host (ex Bluehost, HostGator etc) and upgrade from wordpress.com to wordpress.org and run Ad sense.
3. Move from wordpress.com to BlogSpot and get a domain and run Ad sense.

So which option do you prefer me to go as a long term investments? (The second option will cost me the most I think in dollars!). It will be great if you have some other better options and share.

Waiting for your expert comments…..

Thanks

Dibyajyoti