Quoting instrument prices in a scientific paper
One reason why usually no definitive prices are publicly communicated is that the manufacturers compete against each other when bidding on a tender, where e.g. one lab might ask for quotes from several possible sellers. It would be a disadvantage for a vendor, if their competitors would have knowledge about the specific prices.

Apart from possibly releasing undisclosed information about the prices, another difficulty that I can see with publishing those numbers is that the prices might differ significantly depending on who is asking for the quote and the intended use. Industry customers might have to pay different prices than public institutions, non-profit organizations or individual persons. The instruments might further be discounted depending on how many one would purchase. Also, prices might change on rather short time scales and not be valid anymore after as short as a couple of months.

Therefore, you should take into consideration that any price information available to you might not even be accurate or generally applicable to the audience of your paper.