Do you need a new but?

Are you looking for an adverb, conjunction or preposition that:

1. can be used for joining two ideas or statements when the second one is different from the first one, or seems surprising after the first one?

2. can be used after a negative for introducing what is true instead?

If you are, then visit the Butique and browse the summer collection of ‘buts’. Treat yourself to a ‘but’ that will be the envy of your friends!

I saw the Butique on my walk through the neighborhood today and thought it was a fantastic retail idea. I pointed it out to the tall person and asked if he needed a new but. He laughed and told me that the shop sign was probably a misspelling of the word ’boutique’ and the shop is likely to sell fashionable clothes or accessories.

Hmm, I was going to say ‘but’ but I stopped myself.