I bought an Eden Metro used that came with a flight case. Until now I used the bottom of the case for mobility (heck, it had 3 inch wheels, very easy to move.) I got rid of the case last night and now need some casters to go in the receptacles on the bottom of the amp. Eden has them on their website, but I don't want to pay $35 for the casters and receptacles. Where can I find just casters that will work for cheap?