I don't keep track of what I spend on this stuff. It's not like I'm going to get a tax break on a back-up power supply.
But, you can Google the hardware and see who has the best prices..
If it's only 45w of PV, you should find a cheap charge controller and get a good battery,
and use that stored juice at night to run 20-30 watts of LED lighting.
I've got two 10W panels and finally put one of them to work running the LED reading
lamp on headboard in the master bedroom.
It's nice because it can run for days without sun. And if we have a power failure,
I want a good light working when I get out of bed. (and need to find my flashlights)!
I have not decided what to do with the second 10w unit, but I'm leaning
towards 5 or 10w LED lamp in the kitchen.