I know most of you understand this, but as an electrical engineer, I feel the need to make it very clear...
This is not a job for wall current. Best case, you trip a breaker, worst case, you are electrocuted to death while your house burns down around you. Either way, no picks.
"Wall wart" transformer/rectifiers are probably your best bet. Most wall warts have built in protection, so even if you do short them out, you usually just have a dead wall wart. They cost a buck at any flea market.
Car/moterbike batteries will work for heavier projects, but be careful not to short them out. They don't have any protection, and a short from them can produce thousands of amps.
That being said, have fun and make awesome things. I will be