I don't know, it's hard to picture spending close to $27 on a light for a 1.5 gallon aquarium. That's just me, though!
If you only have Java moss, I've grown that with just ambient room light before. It doesn't grow fast, but it doesn't die either.
A light like this is slightly cheaper:
http://www.fosterandsmithaquatics.com/product/prod_display.cfm?c=3578+3730+17638&pcatid=17638
You can also try finding a clip on book light at the dollar stores.
I've only ever paid $9 shipping at F&S Aquatics, I always wait until I have a bunch of stuff to order from them and make one bulk purchase
Anyway, if you want to grow anything besides the most basic moss, I think you will need to pony up some dough for a light...unless you can find one used. For example, from a failed "SW deco kit"...here's what I mean:
http://www.fosterandsmithaquatics.com/product/prod_display.cfm?c=3578+3730+15493&pcatid=15493
And actually, that lamp can be purchased separately for $12!
