Well, it looks like a British cartoon. The name of the shop is "Rookyu," i.e., "rook you," and to rook someone is to swindle or cheat them.
"Wigan" is a town between Manchester and Liverpool. I'm not sure, but I think that naming the loudspeaker enclosure the "Wigan" is meant to mock the way Tannoy names loudspeakers things like "Westminster." I expect that Wigan is a lot less "posh" than Westminster.
Then the question asked starts out with basic forms of payment, cash or credit, and moves on to H.P., which is "Hire Purchase." In the US this would be something like a layaway purchase where you make a down payment and installment payments with interest.
Then the real punchline: "Let Unfurnished." The joke being that this pretentiously named enclosure is so large and expensive that instead of buying it you might just rent it out as an unfurnished dwelling.
So, the whole thing is making fun of audiophiles, and I assume that it's from 1958, so the 225 pounds would be ~US$4,400 for a loudspeaker enclosure. That's a couple of month's rent for a nice apartment in a moderately large US city nowadays.
That would be my guess.
Edit: And the customer getting fleeced has a Beatles-esque mop top haircut, so it is additionally making fun of the young, fashion conscious "hipster" of the day. The speaker chained to the floor in the front is probably a Quad ESL, which first went on sale in 1957 and might have been seen as expensive, so it had to be chained to the floor to prevent an intrepid mop top from making off with it.
