Any recommendation for a water resistance pressure testing machine?

I'm thinking it might be useful to pick up a pressure testing machine so I can do it myself, after I change a battery and for periodic testing. There are machines available online which say they test up to 6ATM starting around $60. These seem to look exactly the same as ones costing up to $250 but branded differently. I want to get the cheapest version that will do the job properly, I can't imagine using it much more than once a year. Has anyone got any experience of these machines?