Just had quick search Argos is doing 15kg of play sand for £5 which seems ok to me
That's brilliant. Hope you can lug it to your car! Well done! For cuttings, I prefer sand and compost. Perlite is almighty expensive. It doesn't improve the structure of the soil, unlike vermiculite. I would say, put an advert in Freegle as there are always people who have something lurking in their parents' homes or people do an audit of their garage .. I even had Epsom salt which, at that point, I didn't know what it was!