Reddit mentions of Intex 3-1/8" Fun Ballz - 100 Multi-Colored Plastic Balls, for Ages 2+

The cheapest way would be to make them yourself.

https://www.youtube.com/watch?v=eh8yIkrdV9g&t=155s

I purchased these plastic balls from Amazon:

https://www.amazon.com/gp/product/B000066SW0/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

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I run a juggling club at the high school and last night just made 7 sets (21 balls). Only took maybe half an hour and that's because I went slow.

I think the "intex" Russian balls are perfect. They're very plastic and not rubber at all, no problem with them sticking instead of sliding. You can find them at https://www.amazon.com/Intex-Fun-Ballz-Multi-Colored-Plastic/dp/B000066SW0 or elsewhere online. A couple demo clips,

https://www.instagram.com/p/BFSYUQzwwgD

https://www.instagram.com/p/BFrMqhhwwvO

Another good ball is Play's plug & play ball,
http://www.oddballs.co.uk/75mm-plug-play-juggling-balls-p-3740.html

Similar hand feel to intex but a much thicker, harder shell. Here are a couple clips using them,

https://www.instagram.com/p/BBWc3ydQwsI

https://www.youtube.com/watch?v=qKrSpaeItlw

Thanks for the reply. I'll take your word and get those balls instead. I was going to buy the first ones that were 19 something. And are the first ones that come up when you search play pit balls. And will definitely read that post too.

EDIT: so [these were the ones I was looking at.] (http://www.amazon.com/gp/aw/d/B000066SW0/ref=mp_s_a_1_1?qid=1381000863&sr=8-1&pi=AC_SX110_SY165_QL70) seems like they are slightly larger diameter. Are they the ones you previously bought by any chance?

http://www.amazon.com/gp/product/B000066SW0/

These are the balls that I use and I know many people use.

Here is the mobile version of your link

I bought these from a local Meijers for $20USD and followed this guide. I wanted a decent quantity and color selection so I could experiment with weights, give sets to other people, and it's an inexpensive way to meet that criteria. The 3" diameter makes them quite visible and the size has been sufficient for me to learn 5 balls and get started with 6. I can hold 4 of them in a hand using a pyramid, so I can see myself going into 7-8 with these balls too. They have also been holding up very well, I made my first 6 balls about a year ago and only one of them is broken from my shoddy work and one other has had a leak, which I fixed with tape.

Sorry I don't have much experience with professionally made balls, so I can't offer much advice there. I have tried the Sil-X silicone filled balls and have to say it feels rather unique and smooth and they look pretty cool. I've also heard great things about a set of Japanese made Russians from Dan Barron(box/technical juggling god) and they felt very nice; he said they were filled with something other than salt but i forget.

Again, I have limited experience with different russians, but I think the difference in feel between russians is much less varied than in beanbags so I think everything is a pretty safe choice.

I have a set of these. They juggle really well. I find them to be a little slippery when catching more than two in a hand. The thicker shells give them a little more roll than my other DIY russians. Not ideal for foot stalls. If your friend is really interested in foot stuff, they should also check out intex shells. You have to dig through to find good even shells, but well worth it.

So, pretty cheap then? Balls cost about $0.18 each.