justin_t,
Not sure where you are in the world, but I find an unending supply for small 100-250vac to 5Vdc/~500mA switch mode power supplies at thrift stores like Goodwill, here in the USA. Usually for $0.99-2.99USD. They are chargers for cell phones. They usually have flip-out line-plug blades, and are much lighter weight than the normal wall warts for the same voltage/current rating. If you're not familiar with the dangers of line voltage circuits, you should just cut off the cell phone connector, and wire it to your receiver enclosure. If you take it apart and put it in your small enclosure, by the time you add a standard size line cord, you will find you haven't really saved any space...inside the box or outside.
I've even found some that use brand name IC's with standard circuit configurations, that allow me to change a resistor and tweak the output voltage to suit my needs. Being mindful of the maximum voltage ratings of the other components.
Ken