If you're going down the DIY route, buy decent LEDs, not sure on the size but for lamp replacemt applications in the dash some 5mm ones should do it. Osram and Phillips make decent ones that last. You'll likely need some resistors too. 0.5W should be high enough for the current and 850 to 1000 Ohms is usually sufficient.
RS components beats Maplins hands down for price and range IMO
Looks of the following characteristics:
Radial leads (two legs at one end, they only work one way round)
Light dispersal- usually in degrees, bigger is better for this
Clear or frosted lens - clear gives a "bright spot" in the LED frosted disperses the light more but is often dimmer.
Light output - Lumens or candella, depends how bright you want it, 120 is pretty dim - mobile key backlight sort of stuff.