For what it’s worth I just thought I’d offer a couple of bits of advice and opinion from my experience.
You can definitely do Japan for less than two grand. But I guess that you’d struggle to manage it for much less than £1200. I paid about 2 grand in total (inc. spends) but I could have saved money by taking cheaper flights. I flew what was for me the quickest, most direct and most convenient timed flights. But there were several cheaper options that either got you into Tokyo at less sociable hours (which to be honest, in Tokyo makes no difference) or went with a foreign carrier via say Munich or Helsinki. I could also have saved quite a bit by staying in less luxurious hotels.
The other thing I’d like to say is that, do not under any circumstances book a package tour. I nearly did but I’m so glad that I didn’t. Having complete freedom to go where and when you please in invaluable.
I booked my flights direct with BA and my Tokyo hotel direct using their websites. That’s another tip to help with finances. Booking your hotel direct, in some cases, allows you at a small extra cost to make flexible bookings - whereby you have the option to cancel but more importantly you can pay when you check-in or out. This can help spread the cost and allows extra time to save up.
The other parts of my trip were booked through a brilliant company called
insidejapantours. They arranged our accommodation in Kyoto and at a fantastic Ryokan near Hakone, plus they organised our Japan Rail passes, Hakone passes and Ghibli museum tickets. They also provided a superb custom made guide book and some great maps. Another service they offered was a local Tokyo guide who would spend a day with you but take you wherever you want to go. With hindsight that would have been well worth it just for getting me through my first encounter with Shinjuku station!
But more than anything, my strongest advice is to do whatever necessary to get the funds and GO! It is without doubt the most incredible place on Earth (in my opinion). I’m already arranging a return trip for March/April next year.