There are many frases that you could use for something good, nice and cheap, but I can only think of a few...
It really depends on where the emphasis in the statement is.
If something is nice and very cheap you could say "cheap at twice the price"
If something is cheap and worth more you could say "What a steal!"'
Mostly I think though we would say "it's a good buy"
I logged into this forum because I was also looking how to translate this. Bueno, bonito y barato not only has the specific meaning of its 3 words but also all start with B and this gives added emphasis to the expression. I would agree with Missjen and think her proposal of "cheap at twice the price" and "it's a good buy" could be good ways to express it. I have lived many years in Spain and have often heard the expression used for people who want to get everything at little expense or effort. Although it could be used by a buyer or a saleman, too.
I would propose an alternative as a "bargain" or a "good bargain" or "a bargain deal". And am going to use in my translation the following hybrid "such a good bargain that it is cheap at twice the price".
Nice detail: efectively in Arabic the P and the B are sort of fused together into one particualr sound.
Your anecdote can easily be felt by anyone who has been assailed in Tetuan or Tangiers by street sellers and souk tenders and a certain style of peddling where whatever sold is always a good bargain: bueno, bonito y barato.
I have lived many years in Spain and have often heard the expression used for people who want to get everything at little expense or effort. >>>> This would be a bargain shopper.
And another way to express that something is at a cheap price: Bargain Basement prices. . or something like this. (or maybe even Bargain Basement Buy . . there's the 3 B's for emphasis, but I may have just made that up!!) I'm sure there's another forero more familiar with this phrase.
From what I noticed in Spain, the guys (usually of African origin) who try to sell you stuff on the street, beach, etc, say "bueno, bonito, barato" if they think you are Spanish, but if you look like a guiri (Northern European tourist-type, usually British) they say "lucky, lucky, lucky" ...so it seems that they haven't come up with a good translation for it either.