The cheapest option is to buy a tarp from any good DIY store and cut it to size.
Just make sure that you cut the tarp so that it is about 2" smaller than the actual tent all the way round to prevent water pooling.
I have one I would be willing to sell. One of the pegging straps has ripped where we didn't pull the peg out when folding it up and we accidently ripped the webbing strap, but it's still usuable just not able to peg down at that point.
Because of that we could do a deal on price. Also have a carpet if you're intestered in that too.
based in Birmingham, but could arrange a courier at an additional cost.
Hi Dubs1978 - how much would you be willing to sell it for please? Carpet not needed, as we have that. I would need it posted, as I'm in Bristol. If you have an ebay account, that might be the best way? x