I've found Rit dye works well, but is not concentrated enough to produce deep colors.
Moser's aniline dye from Woodworker's comes in purple. You can mix it as strong as you like; more powder in the mix produces stronger color. Water-based is the most light-fast, but will still fade if a finished piece is kept in direct sunlight. Even a light coat of asphaltum (mixed into thinned tung or boiled linseed oil) seems to improve the resistance to fading, as asphaltum is totally light-fast. Of course, asphaltum isn't purple. In stronger concentrations it is reddish brown, and thinner it tends towards amber, so it would brown out your purple a bit, and give a more natural woody look.
The color-tone dyes from Stewmac work well. They are mixed right into the top-coat. I've used them with water-based lacquer & like them a lot.
Maple is a good choice for dyeing purple, as it is nearly white to start with. Aniline dyes and colortone in the finish enhances any figure that is in the maple and makes the curl "pop" and look deeper and more shimmery.
The deep transparent colors you see on some electric guitars is tinted lacquer, such as you could get with the colortone dyes.
Of course, you could also just use purpleheart, which is purple from the get-go.
I prolly have pics of some of these on maple if you are interested.
What's a get-go?