budget for a 10 days tokyo and hokkaido trip?

Hi, would love to know the rough budget if i would to travel 4 days in hokkaido (sapporo, otaru & nboribetsu) and the remaining in tokyo.Coz if they are too expensive, then i would have to just travel around tokyo. I have roughly 253,000 yen for 2 pax for hotel, food, transportation around japan and admission fees. I have already bought the tix to haneda and back to my country.
I plan to stay at backpackers house ie, toco heritage. So i am comfortable with accommodation like this.

So is it possible to include hokkaido to my itinerary or should i just stick to tokyo? will be arriving in haneda from 4th Nov midnight and leaving haneda on the 14th 10pm local time.

I personally feel you have enough money to go to Hokkaido for 4 days. I'm always on a budget whenever i travel to Japan so i think its feasible. You can try searching for cheap domestic flights from Haneda to Sapporo. Try JAL, they have Super SAKITOKU Advanced purchased fares for as cheap as 22,240 yen per pax for a round trip. :)