Actually you can buy one for it. Manchestervacs will ship to the USA and provide excellent service and proper genuine Dyson parts in perfect working order. Take a look at their Dyson forum- it's really good!
Un clip the cyclone top and take the filter out (machine wash it if you like) and there are 7 screws underneath the filter. They are a torx T15 type.
The top part removed and everything on the cyclone un clips, from the very top of where the filter sits all the way to the bottom bin flap gasket. Everything can be removed by hand after removing the 7 screws. On a Dyson, anything can be replaced. There is nothing on a Dyson that cannot be replaced.
Best wishes