Hopefully someone can suggest a solution.

I'm trying to replace rotten wood on a 6 by 4 wooden shed similar but not
exactly the same as this one:

http://www.wickes.co.uk/Timber-Sheds...ed/invt/543343

The sides are easy enough to replace - there's only one side that has
rotted. Cost of replacing the side is about £25.

But the floor (again one side) has also rotted. This is more tricky. You
can't simply buy a replacement floor. My diy skills are not good and I'm
stumped. How to replace the rotten floor of a wooden shed (only the end 1/5
is rotten). I think that cutting out the rotten wood and adding good wood to
the existing good wood may be the answer but I'm probably talking ****.

Also the support floor to roof beams have rotted at the bottom but again
only on one side and only the last 6 inches or so of the beams.

The price of a new (but very basic shed) is £125. The cost of repairing the
existing one is about £60 I think (maybe a bit more depending on the cost of
repairing the floor). My skills are also very poor indeed.

Would it be easier to buy a new shed for £125 or repair the existing the one
for £60 to £70?