Where can a guy find some old used milk crates for storage in my portable shak?

Try the grocery stores!

Plus I think targets and walmarts and places like that sell crates that are pretyt much the same size and shape, so they should serve your purpose too.

To add to what PJ said, the ones you can buy (for cheap) are just a bit lighter than the milk crates as well.

I looked around recently for the plastic kind to mount to the rear rack of a three wheeler for putting ice fishing gear in and holding 5-gallon buckets. Target & Walmart were a no-go.
Found them at Menards, bought two for under four bucks each, they even had black to match the rack. Worked out sweet! Office supply places also carry them, used as file holders.

I would also reccomend going with a rubbermaid tote. They have a lid you can bungee on, keeps the critters and snow and everything else out of your gear!

Sounds like dumpster dunk'n to me!!!!

I get them from a milk company and when they get some nicks and cracks in the crates they will let ya have them. I would call some milk companies.

here's a spin on it- anyone know where the metal flavor crates can be had?

Once again the Milk distributors around my area have them at times but getting the hard plastic ones from them after a crack or nick in them is much easier than getting them to part with the metal ones.

Find a Kemps Milk Man that delivers in your neighborhood and order some goods from him. He will deliver them in some Milk Crates and then, as you go each week, you can keep some of them. I have "hooked up" many of neighbors with them and they work great.(they are the hard plastic ones)

Menards has them for about $4. Target doesn't have them. I bought one for my son's 20lb propane tank.