Inner tubes and the rise of China

Is it just me or have babies got more expensive in the last four years? I'm guessing it's got something to do with the price of oil or possibly the rise of industrialised China.
I only mention it because Saturday saw the first of what is likely to be many trips to Mothercare, now that the latest addition to the clan is well on the way.
We dug the old pushchair out of the loft to find all three of the tyres were flat, and no amount of pumping would get them to stay up for long. Long enough to get to the library then half way back before having to physically drag the fully laden beast, kicking and screaming, along the mean streets of Devon.
So the kind lady in Mothercare advised us that after three years the inner tubes may have perished. "Hmph", says I.
"How much?" says the heavily laden wife. To which we are informed that inner tubes will cost us £17 each. "Argh", says I, wandering off to look at the new pushchairs mumbling something about it being cheaper to buy a new one.
The idea of buying a new buggy deflated faster than three-year-old inner tubes when I started flicking over the price tags and finding that 649.99 wasn't the model number but the price.
Fortunately back at home I logged on to eBay and managed to find three inner tubes, plus delivery, for well under £10. Derek, the man who will supply them, assures me they are now on the way.
I'm sure having the first one wasn't this expensive. Must be the oil thing. I wonder if you can get babies to run on used cooking oil.