I did not price all the cables at A2Z cables.com, but the 12 foot component video (Belden) they advertise at $95.00 is available at Blue Jeans cable for $60.00.
So if your building a specialty cable that may not have great resale, I suggest paying as little as possible, especially when they are identical materials and terminations.
To answer the original question, Purist Audio builds an RCA (female) to XLR (male) adapter, and it sells for about $100.00 with a discount. This is a valid option if you already own an expensive cable and don't want to pay to have it re terminated and /or wish to retain the XLR configuration (using converter only when needed).