Junk stores and antique shops are rare around here. When we visited the USA I was amazed at how easy it was to find things like blue mason jars and stoneware, milkglass, old scales, old burlap and flour sacks, etc. It just doesn't exist around here in mass quantities.
That being said, how much is too much to pay for an old wooden crate, like the wooden soda crates and fruit crates? I have never seen one around here - a local lady was banging some together out of scrap wood and spray painting logos on them and i have one of those, but I'd really like to own a "real" one. I found one in a cute little shop today -- the lady goes down into the States actually and buys up tons of stuff and brings it back to sell, and this was the only one she brought up. She is asking $20 for it which I thought was a bit much. But on the other hand, I could not come across one for years . . .I've looked forever and never found one.
I paid a good bit more than that for one in Astoria. Almost $50 I think. It had a logo on it from a factory that was near our house, so we wanted it. I keep all my cleaning supplies in it under my raised oven and I still love it, so I it was worth it for me. There are also a ton on eBay, so if you wanted to get an idea of the going price, you could check there.
ETA: I think the size and logo matter too. I'd pay a lot more for a "Coke" crate or one with a neat looking fruit logo than I would for some of the plainer ones.
Actual old, actual wood milk crates/soda crates/fruit crates are worth a fortune here. $20.00 is good I'd say as a lot of them sell upwards of $50.00plus here esp. if it's a famous logo or something with local history.
I have one I dug out of my grandmother's basement years ago and people ask to buy it off of me all the time..lol.