I myself was quoted prices above the $400.00 price point.
If that was the only outlet I think I would invest in very large plastic lunch bags and call it a day. However that that not being the case and let's face it I wanted something that not only gave me protection but looked nice, professional and COOL.
I stumbled on radiodustcovers.com and communicated with Stan Clewett on sizes, monogram, and style of which there are three style of fabrics...even waterproof if your tube amplifiers on by poolside...lol.
They are very affordable lite weight, serve the purpose and have a professional look.
In the event you are out there looking for dust covers and are frustrated with ridiculous prices you should check out Stans workmanship.