Ebay's probably the best bet.
I'm still smarting at paying 85p per metre for 6mm line for lazyjacks from the local chandler. Needed it right away, though.
When I relaunched my boat in '02 after she was laid up I replaced all the ropes and strings. It saved me a fortune and is a much easier way to buy rope than from the chandler as he sells odd lengths at fixed prices, so you know exactly how much it will cost.
You can always spot him, his trailer is always in sight of the entrance.
If you can wait (and I guess you can't) the Sea Cadet stand at SBS have some bargains of real rope in a variety of sizes (but get there quick to beat me!).
If you want jackstays with an eye each end £8:99 + VAT for 6.2 metres. Proper thigh harnesses complete with lanyard £35 + VAT then speak to Kevin at Cosalt Bristol at 01275 848488
The other day I noticed that my local B&Q has nautical looking rope, braided, laid and octoplait. It even stated on the labels that it was suitable for marine use. Didn't notice the price, though, and wouldn't have known if it was 'cheap' or the other.
Re: Cheap Rope? - check what types of rope are available
might be worth researching what types of rope are available first before buying cheap. I thought all braided marine rope was the same, but not so after a quick conversation with a local supplier. for example, halyards should use non-stretch versions. Dont remember what else to look out for as Im not buying at the mo, but others may be able to fill in the details......