I don't use them for sleep, but if you can get your hands on a bottle of Radians Resistor 32's, they're the best cheap earplugs I've been able to find. Way better than my now useless $60 custom made ones. I get them from Gander Mountain, but any sporting goods or shooting store should carry them. About $5 for a pair of 25.
Just make sure to clean them if you re-use them.. gave me ear infections when I re-used them. Make sure they're not too big and you don't have to cram them in either. Hurts like a b**** the next morning.
I don't suppose it would be helpful to sarcastically suggest that you move to a quiet area. Disposable foam ear plugs are dirt cheap and can be purchased by the case lot for a few dollars thru contractors suppliers
I used foam ones, but they last only so long.... I still have wax ones, they're pretty good, but you can't clean them and if they get too warm, they tend to go out a little bit. I mean, it's like they're lubricated and they're slowly slipping out of your ear. Fraction of mm is enough for you to hear stuff. Also, sometimes they're hard to get out. Mine aren't completelly way, they have fibers inside so you can get them out more easily.