I have a good discount with the Fitness Mad group of equipment providers, which I am happy to pass on to my students if you buy through me.
You can take a look at their stock at www.fitness-mad.com. P&P may be extra for one off orders, but will still be cheaper than many shops, and you have a lot of choice. Let me know.
Plus this is where I buy the magic spikey balls. I am usually happy to sell these directly from my own stock. £6 per pair.