I personally am not a big fan of par cans. That would not be the route I would choose to go in however, for a limited budget that would be your answer. If moving fixtures are out of the question for you then I would suggest checking out some LED products. The link that was posted to elations LED product in this topic is an excellent idea. I know your big on going with the color blue... However, I feel it would be in your best interest to have the ability to change the color on a moments notice. With the use of an LED fixture you can achieve this. However, if you feel you would never even remotely want to change to another color other then blue then I would suggest going with the par can route. Par can's will provide you with washes of "blue" light in your case. As for control of them did you have any thoughts as to what type of control system you were going to use? Did you plan on using dmx dimmer packs. Or non dmx relays, for example adj's light copilot and similar controlers. How big of an area are we talking about here? overall dimensions and ceiling height? Just another thought I know your overall goal here is to add some interest to the space. Why not add another aspect to it such as water features. Water Panels and columns. Suttle waterfall effects. If you check this link... It will take you directly to specialized mood lighting. If you use the navigation on the left side you can find all sorts of water panels and water features.
Mood Lighting and Water Panels