To begin with why would you want 'the cheapest plates available'? cheap plates are inaccurate (eg, a 25kg plate isnt 25kg) and the rubber literally rots. In the end you dont save money.
As Australians have a tradition of rubber coated weights (less wear and tear on floors and bars) and because they're generally in the same price range, I'll walk you through some ones I like:
LFS Sydney - Hammertone olympic plates $2.30/kg
LFS EXERCISE AND FITNESS WEIGHTS
Definitely the cheapest plates around and they look okay, though I've had no experience with them. I'd contact the seller and get them to tell you just how accurate they are.
Gymandfitness - standard rubber coated plate $3/kg (gymdirect sells these too)
Gym Equipment, Fitness Equipment, Home Gym Equipment, Power Racks, Multi Gyms, Weight benches
These guys have quoted me that most of the plates which come through are 1-2% accuracy and never more than a 1kg off. They seem tough, very thin and there are lots of package deals you can get where you basically get a free barbell. If I had my time again I'd buy these exclusively.
Shu Trading - rubber coated olympic weight plates ?/kg
Shu Trade,gymnastic rings,plyometric boxes,clubbell,kettlebell,weight vest,plates,rack,power sled,sled,medicine ball,medi ball,rubber mat - Home
I was recommended these from a big name rugby coach and crossfit affiliate in Brisbane. He swears they're better quality than the ones from gymandfitness and as they're completely identical to my york plates I'm inclined to agree. My only whinge is that they're quite thick.
Sizes to get weight plates:
- 0.25 x 2 (make these out of chain at Bunnings)
- 0.5 x 4 (with the 0.25s these make microplates)
- 1.25 x 2
- 2.5 x 2
- 5 x 2
- 10 x 2
- 15 x 2
- 25 x as many as possible
Notice that I skipped the 20s? they're unnecessary if you've got 15s and 25s and if you wanna put 300kg on the bar down the track (and if you dont gtfo) they'll serve you much better. Wont fit on a plate rack though.