I am not a huge backlighting fan, but I am going to backlight my board from sprit and use thick abs keycaps on it, GMK classic beige to be exact. I like the glow from under affect WAY more than glowing through the keycaps.
Although, I am going to say, I don't think any configuration of sprits board is going to be cheaper than a poker 2. Poker 2 can be had for 100-120.
Minimum price for sprits board
$50- PCB
$20- Cheapest Plate available from sprit (acrylic, not even metal)
$45- Lets say this is the cost of switches
$10- Leds
$???- What case are you putting it in???
$8- Stabilizers
$20-40- Shipping
There is probably even more cost behind it, soldering supplies, etc.