Cog wheel bearing size?

[Fishit 2]

Hey guys, tried searching the site and couldn't find the answer but I'm planning on making my own and plan on shaving a cog to accept a bearing. Some sites are charging up to $40 for this part and I figure I can make my own and buy the parts separate, I just need the correct bearing size, any help would be appreciated, thanks

[0119]

You can get them for only a few bucks at hookless.com.    He also has the manufactured cog to fit, they are not very expensive.

[Keta]

I'm easily confused, can you post a link to what you are doing?

[Fishit 2]

If you consider $17 cheap I wish I had your money. I figure I can buy the cog for $5, the bearings (3)for under $10 I would then have to shave the cog to allow the bearing. Here is what I'm talking about:
http://www.ebay.com/itm/171481340138?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[Bryan Young]

Oh, I was wondering what you were talking about.  Those come with one or two bearings.