asda have some great deals atm,
in the 2 for 3 pound bit they do 20 blue pens for like, £2, or £3 for 40!
for the paper go to tesco and get the pucka bad 400's for like £4
some good deals at asda though, 2 for one on the sharpes and ect. take a look
also £1 for 24 pencils
staples also have a 60% off deal as far as i know?
aldi have got some good deals, 90p for 160 (2x80) sheets of paper (wich ar 60gsm, but havent checked them out, dont look paper thin though tbf)
Honestly, I wouldn't reccommend buying cheap school supplies as they don't last that long. I've bought cheap lined paper and ball point pens and the paper is so thin that it falls apart after flicking through the pages in a binder and the pens sometimes don't work at all or they run out quickly. The best paper is by a brand named Oxford, it's really thick so your ink doesn't sink through onto the other side of the page. I just look round different supermarkets when my parents go food shopping during the summer and then pick up whatever they have that's on offer and then I end up with everything I need.
Our school actually retailed the vast majority of the stuff you listed. The school doesn't look to make profit, either, so you can get certain things like calculators and folders for a couple of quid cheaper than elsewhere.
I guess it just depends on the size and availability of your institution.