One of the main considerations Sambu is how long you aim to ride for...its the batteries that dictate most of the cost of decent lights. Do your homework on and make sure whatever lights you choose...that they actually can last the duration of the ride.
I had a set of cateye halogens with a heavy Ni-cad battery...sadly even though the lights were quite good by the standards then, the battery rarely lasted the distance.
DIY Cree LED lights (or similar)are do-able, fabulous light throw and good life with the right battery, but even DIY they come expensive...
2x 3W Cree LEDs, maybe £15
Some sort of housing, maybe £5
Switch and LED driver, maybe £15, then you need some sort of heatsink, possibly jackplugs too connect/disconnect the battery...and finally the battery itself, mines a 15V Li-on battery, nice and light, compact, long lasting (hours and hours of high power lighting)...and you'll be looking at £30 ish minimum for a battery. (to be fair, my battery is a bit OTT therefor more expensive than it needed to be)
I reckon my 2x Cree setup cost minimum of £60 to build. Fabulous light output, but at a cost.
There are many cheaper options, homebrew or mass produced, but good lights cost either way. But there's nothing worse than spending good money, to find they're not going to last long enough.