'cheap, good, bright'.. pick any two.. There is a thread for a 3W solitaire mod.. hasn't been posted to in about a month.. I think waiting for parts, just like me for my 3Wlux mod for peak lights. I've seen people make 3 or 5mm LED mods cheap for solitaire.. unfortunately.. LEDs require more voltage than an alkaline can output, and it's really hard to find the likes of 1/3AAA bat to stack an boost the voltage (1/2 and 1/3AA are easy to find).. I personally would wait for LiON AAA to be available and go that route.. the battery seems expensive but you can re-use it hundreds of times so it's actually cheaper than alkaline with the benefit of having three TIMES the power capability. you can make a 5mm or lux mod as simple as a LiON AAA and a resistor.
-awr