Hi, havent done it yet, but im planning to go that way. It seems to be something in the neighbourhood of
-2000kms thru Turkey,
-some 3000kms in Iran,
-nearly 2000kms in Pakistan.
And i think it could be around 1500 in India, if you´d go straight to Nepal.
Note that all these are following the straightest possible route, and if you do any detours, it could be much more.
Im expecting to cover 300-500kms per day in Turkey & Iran (if needed, but Im actually hoping theres some time to spend in each country) and maybe 200-300 per day in Pakistan, as the roads could be worse there, and there might be police escorts, which go slowly I hear.. (and I´d be happy to hear someone who´s done this route, comment if these figures could be considered realistic or not?)
In India roads can be relatively ok, but the traffic is very, very bad & congested, so not planning much per day there, either. In a country like India its very easy to get lost, too, when theres junctions here and there all the time, and no signs whatsoever. Add that to the crazy traffic, and it might be very time-consuming and require plenty of patience to cover any distance there!
About money, I really dont know, perhaps someone more experienced can help..? But in theory anyway, these countries are cheaper than almost anywhere in Europe. Probably depends a lot on your choice of accommodation, etc as well.
Get up early, and start looking for a place to stay well in time, so you wont have to ride in the dark.. or at least thats the plan, though it usually never really works that well