Where I work we sell what we belive were motor start caps. There is some light industry around where I work and every now and then some one asks for a motor start cap. Theirs is usually bulging if not completely destroyed. Most times we can match the size usually about the 10uf mark. We have two types, metal can the black resin encased.
http://www.suntan.com.hk/pdf/Plastic-Film-Capacitors/TS11.pdfIt appears according to the site above whose caps we sell ours are motor run. I understand you can use motor run as motor starts but not always the other way around. I had purchased some from work years ago but didn't use them believing that were motor start and wouldn't handle constant voltages. We now know they are runs and I can use them . They are in bright shiny metal cans but I would stil, probably, spray them if to be displayed atop a tube amp.
The biggest is 30uf, perfect for most tube rectifiers as the first cap. Our list price is A$17. Not over expensive even if you used two.