Support your local garden centre rather than the big boys if you can - just picked up 3 crowns of asparagus, a bag of vermiculite and 4 hessian sacks for £3.50. Planted the asparagus out for OH and pleased with a job well done until she pointed out it was upside down. Australian anyone ?
I also found that I would save around 30% by buying tanalised timber from my local supplier who has a limited website, against a less local supplier with a much swisher website. If you're in the East Midlands then try contacting Gary/Graham from Coltman Bros