They all seem to cost the earth these days - now there's a surprise. In 2020 I bought a 6L ultrasonic bath through ebay from a firm called Industry Press. It cost me £83. The same thing now costs £137. Ebay has quite a selection of 6L ultrasonic baths, most of which look remarkably similar and cost around £137 upwards. The 6L bath is 30cm long (Interior measurement) and therefore big enough for most 4mm coaches. In conjunction with the appropriate fluid it has worked very well as a paint stripper and is also useful for cleaning up etch brass kits, etc before painting. However, useful though it has been, I'd have to think quite hard about splashing out £137 on one today although if I was to be doing a lot of paint stripping I probably would.