i don’t know why, but i’ve found better flight deals when i’m actually in asia than i could obtain through sites like expedia or lastminutedotcom when i was in the uk.
i have no idea whether this applies in your case, and if you do fly using local airlines after you arrive in asia then for god’s sake avoid carriers like china airlines who have a worrying safety record.
delhi to beijing overland is possible, though it really would be an *adventure*. forward planning on your visas for the countries you route through would, of course, be essential, though countries like laos allow for a visa on arrival at places like vientianne.
good luck. i quite envy you 🙂