There are a few sellers of the powders on ebay, you can mix those powders with a clear acrylic, but you will probably want to use a brush with a 0.5MM needle and nozzle setup or larger. You could also mix the powders with a clear automotive urethane finish for a more durable (and expensive) paint job. The pigment size/dimensions and the medium's viscosity will play a strong role in how you are able to spray it. You typically need to shake the paint on a real regular basis. The weight of the pigment makes it want to settle if it sits for very long.
You might look at glowmaniaUSA and Readysetglow, both sellers on ebay.
I think Krylon may make some paint too, but I believe theirs is in spray can only.
If you are talking about UV/black-light paints then there's a huge variety out there you can choose from.