There's another thread on this if you search for it. I don't think the guy ever found exactly the right struts but can't remember. I would try some different shops because some of them can search based on length and diameter of gas chamber.
Similar Thread:
trunk lid lift supports
This one looks promising and only $15:
Stabilus Master Lift 20 Center to Center | eBay
Its made by Stabilus, the same manufacturer. They say it measures 20" center to center. I presume that's extended. If so that's exactly where the one on the Roadster sits when extended. You may want to ask the guy if he can get the same one that's on the Roadster.
Here's the numbers off the Roadster's strut:
Made by Stabilus in Germany.
Believe this is the true part number - 6794 YD
0180N 049/09 DC 14
The number below that one is: C126B6004F
The "
0180N" number is similar in the ebay listing part number of: 4525 QV
0180N 332/11 C 15
Also you can try calling/emailing Stabilus and give them the numbers.
Usually you can just measure the extended length, compressed length, estimate the load and your good to go with finding a random strut that meets the spec. The Stabilus is a very good design, it has a spring inside the hydraulic body that helps lift the lid when temps are lower. Hence why the body is fatter than the traditional strut you find on regular car hoods and truck camper windows.