I'm not sure where you're from, but I started picking on cheap five-pin locks I'd removed from door handles and dead bolts. You can learn to re-pin (see this thread
Repinning) on these and you can remove all the pins except one and slowly increase the difficulty of your lock. There's a sticky thread on that somewhere too. I also like hardware store brand padlocks. They're a little cheaper than the master or similar name brands, but the quality is the same (or sometimes better) and they're likewise easy to pick. Again, you can start on the smaller three pin locks and then work on five pin locks.
Finally, go anywhere where there are lockers that you can put your own lock on (gyms, pools, etc) and ask them if they keep the locks they cut off, or if they'll start for you. These places inevitably have a policy that runs something like, "If you leave it locked over night, we're cutting off your lock and keeping your stuff." Tell them, you want to melt down the brass for sculptures or some such lie if they're reluctant to give them to you.
Locks keep honest people honest.