Those are pretty good prices for genuine Kabelschlepp drag chains.
I have just ordered some 'knock-off' ones from China on ebay:
2000mm or 80" of 10x10mm drag chain for £4.08 each + 2.08 P&P
here (total inc P&P of £10.26 about $16.00 or about 11.20 Euros)
1000mm or 40" of 15x10mm drag chain for £4.25 + free P&P
here (total inc P&P of £4.25 about $6.50 or about 4.60 Euros)