Pasting from Photoshop into Illustrator producing bad colors

>My printers are all CYMK

Design in CMYK.

ThreadConnect,

I believe there are two aspects here.

"It's very stressful because I create this beautiful image with a vibrant blue but it prints as a dull purple and with many other colors as well"

This is unavoidable because CMYK has a much smaller gamut (range of colours), especially lacking some vibrant colours.

If you really wish to print vibrant colours, you will need to use a printer with other/more inks than CMYK.

Or you will have to suffer it.

The best way to reduce the suffering is to start out in CMYK in both PS and AI.

And at the same time this is the best way to obtain the greatest possible control, and consistency across different uses/media.

If you wish to have more vibrant colours for screen use, you can create a separate RGB version for that afterwards, so that becomes an enhancement made to match as well as possible, instead of creating a reduced CMYK version which may always seem inferior.

And what Michele and Ton said.

If you are using RGB in Photoshop and CMYK in Illustrator, you are going to have this problem, they are two different color modes and there are far less colors available to you in the CMYK color spectrum. I would suggest, even if you need to use an RGB document in Photoshop that you then use CMYK colors or convert to CMYK colors and color correct in Photoshop to get colors that you like before bringing into AI. That is really the best way to get the best results in a CMYK document.