I sell them for 20cents + 3cents fee

Low series number crates like those should draw much more than the pennies the newer ones do. I think series #1 crates had formerly been going for upwards of a key, but it is hard to say if that is still the case since the market is making the prices of keys and metal go a a little more crazy than it had. My suggestion before you sell any of the lower series crates is to wait til they put in a crate series search function so you can better gauge their worth and they will be easier for potential purchasers to find.

I put all them for 0.10 because meh..

3 of them were bought in 5 minutes... i guess i had rare crates xD

This should help: http://tf2crates.blogspot.de/p/crate-price-spreadsheet.html