It's not 500 lumens. The one watt version is around 50 lumens, so I'd expect the two watt version to be around 100 lumens.

The P7 flashlights are around 400 lumens on high. This one isn't actually P7, but BIN-M (or is BIN-M a type of P7?) which is similar but newer and a bit more efficient for $20. You can buy two of those and a pack of batteries for the price of the PB Blaze 2w. Throw in $18 more and get two more batteries (spares!) and a charger. Well, you'll also need a $1.50 mount. Might as well get two, as you've got two fully functional lights.

And don't delude yourself about the Blaze -- thieves know it's a good light, and absolutely will steal it. Yes, it's better built than the flashlight I gave above -- but it costs nearly twice as much and puts out much less light.

If you want a cheap bike light, get this or this. The light they put out is comparable to the original PB Blaze 1w, though taking 3xAAA rather than 2xAA is certainly a minus, and they're not as rugged as the Blaze. These are less likely to be stolen than the Blaze as well, but they're still pretty likely to go.