The first lock appears to be a Tri-Circle lock, which has spool pins and you would probably find to be difficult. (See
viewtopic.php?t=8140&highlight=tricircle)
For the second link, I am not familiar with the Sterling brand. Try searching around a bit to find out more about the lock, like whether it has security pins or a difficult warding.
Again, I'm not familiar with the Squire brand locks (Link#3), but I'm sure someone here is. The 4th one could be easy or it could be hard. That is a lock design that is made with varying quality levels, and without knowing the brand it is difficult to judge the difficulty. As for the last one, that isn't a pin tumbler lock, it's a lever lock, and according to the stamp it's 4 levers.
One of the better ways is to read about what locks you are interested in, and then search for them on Ebay. Often you can find locks cheaply there. Also, you might want to consider getting a deadbolt lock, (Like a Schlague) removing some of the pins (a good way to get a strong understanding of the lock), picking it, and then adding more until you can pick the entire lock. Then mix the pins around for practice, or add security pins.
loads of help. I'll check out ebay now.