When you contact a commercial printer and ask them to print in RGB, you’re not going to get very far because they actually can’t print in RGB. Printing presses will not look good at all if you tried to print only using Red, Green and Blue ink. Because printing dots onto paper is a subtractive process, it really only works well when you print using Cyan, Magenta, Yellow & Black ink in some combination onto white paper. The only main imaging process I know of that works in true RGB is imaging onto photographic silver halide paper, which makes use of dyes that develop in the chemical baths. If you really want RGB printing, you could have this done at a one-hour minilab using a Fuji Frontier, or a Noritsu printer. Or in a commercial lab that prints onto photographic paper with a Durst Lamda or a Oce Lightjet.
Having said that, I don’t think you’ll get the green saturation you’re looking for from these RGB processes, as they are not a lot better than a typical CMYK press, and might not work with the material you’d want for a business card.
The pallets that you see when you switch back and forth between RGB and CMYK in Photoshop are switching between the default working spaces as they are set up in Photoshop. The RGB that you see in Photoshop is probably best thought of as “typical monitor color” and the CMYK can be thought of as “typical printer color.” Since monitors can produce colors that printers generally can’t (and vice-versa in some cases), that lime green might be an unrealistic color to expect any printer to print.
On the other hand, the numbers you see and the colors you see there are not necessarily what you’re going to get when a lab prints your work in CMYK. They might in fact be able to give you more color that you expect. So I would recommend picking a good quality lab and see what they can do for you. A lab that knows what it is doing is used to accepting RGB files from customers and converting them to their CMYK printing in a way that looks good. If you really need that lime green to pop out, they might be able to print using a spot color.
The most saturated gamuts of any printers are currently found with inkjet printers, so you might start by looking for a lab with those.
Here is more information on the difference between RGB and CMYK:
colorwiki.com/wiki/Color_Man … _than_CMYK
And here is an illustration that might help.
The small squares represent a full list of Pantone solid colors with the more neutral colors toward the center, saturated ones to the outside. The six-sided shape is the gamut of a high-quality press. As you can see, there are a lot of Pantone colors that are outside of the ability of even a good quality press to print. Pantone produces their books by using as many as 16 spot colors.