Dear Sir/Madam

We greatly appreciate your quick response for your cost quotation of our audio equipment research in the Russian market.

After having several discussions with our client about the terms???,

we regrettably decided to ( accept / adopt ) another company's suggestion.

However, as your idea was also an excellent one,

if we have a similar ( case / project )??? in the near future, we would like to ask you

an inquiry??? about it.

We would like to maintain a good relationship with you,

Best Regards,
AnonymousHi, could you do me a favor?I'd like you to correct the following business letter. I wrote '???' where I'm not sure. --
Dear Sir/Madam [Since you have already had correspondence, you must surely have a name to write to]


We greatly appreciate your quick response and your quotation for our audio equipment research in the Russian market. However, after discussion with our client, we have decided on this occasion not to accept your offer.
Nevertheless, if in future we have a similar project, we will certainly approach you to discuss it.
Many thanks for your interest.
With best wishes,

Yours sincerely.

Feebs11, thank you for correcting my letter.

The letter reads far better.