Hi Lee,
I think the center spindle is about £15.00 and the bushes are another £8.00 if I remember correctly. I've also had my hose reel about 5 years and I am also considering adding a spindle and bushes to my spares kit just in case.
What I ask myself is what it would cost if you couldn't work 1 day because of a failure - it would cost far more than the cost of the parts.
When I first started WFP I somehow broke the Y piece from the hose to the jets - I've never broken another since. I only had 1 brush and 1 pole. I didn't have a spare and hunted everywhere local for something that would work - nothing, not even in B&Q.
So I got onto the Internet and ordered a few by first class post later that afternoon - they took 4 days to arrive. In the meantime I managed to source a Y Piece from a local motor factors all sorts box for 50p a day later.
I learnt a valuable leason from that as I lost a day and a half's work for a part that cost 'nought'. I probably take carrying of spares a little too far now.
I always ask the question, what will it cost if I don't have it and can't make an immediate plan.
Spruce