That is not a bargain. Not that it would fit your shelf, but, the typical "on sale" price of a shoplight that uses two 40 watt tubes is about $10 and the "on sale" price of cool white tubes is $1 - $2.

At equal input wattages, there is little difference in plant growth rates between different fluorescent lights, e.g., warm white, cool white, "plant light" etc.

You would be better off using two 26 watt compact fluorescent (CFL) lights that can be bought for $1 - $2 (I bought $1 26 watt CFL Lights of America from Walmart). Sockets for mounting on your shelves will probably cost around $5. You should mount the bulbs horizontally to provide more vertical space for your plants.

I use these lights myself, and they do work, but I plan to overdrive them, and install T8 tubes.

I use 3 on a 2X4 shelf.

i have two fixtures from wally world. they are lights of america brand. the couple i have are rated for t-8's and 12's. i used 12's last year with success. just keep the bulbs close and the air temperature in the room below 75 degrees. how many lights per shelf? depends on how big your shelf is. one fixture with two bulbs should cover about a foot wide, give or take. that is my experience. while your at wally world, go to the camping section. get you some mylar emergency blankets. they look like aluminum, or use aluminum foil. drape around the fixtures or walls or light box/shelf so mylar or foil reflects light. the plants can almost touch the mylar, so be generous. hope this helps.

Thank you for all the help. I will use 2 per shelf since these are only 1 bulb per fixture. I will also look for the other lights mentioned at Walmart and try those on a different shelf if they are cheaper. I was going to wrap the back part of the shelf in aluminum foil, but will look for the blankets. Thanks!!

I was going to wrap the back part of the shelf in aluminum foil

The shelves should be painted white inside. For your purposes, regular white acrylic would suffice. But, there are special, hard to get paints with more reflectivity than aluminized mylar or aluminum foil.

I have a few fixtures from Walmart, they're Lights of America brand, but they are all T-8's. To my knowledge, T12's are being phased out. Keep in mind, these fixtures are CHEAP! Beyond a price issue, they are very cheaply made. Get a few from Lowes or HD, they may be an extra $15-20 but it's worth it. The LOA ballasts flicker or turn off every time I raise, lower or bump them. Yes they are made in the USA, but out of the cheapest Chinese components available.

Mylar works great for lining walls and shelves and can be found at hobby and party stores. I have found that the LOA 7114 or 23" T5s work better than the T8s and only costs $9.95. I think the lumen rating on the T5s are incorrect at the site given above and should be more like 1400 instead of 700. They are actually overdriven by one watt and are brighter than similar T5s from Lowes. The LOA ballasts are 14w and the bulbs are 13w. The models at Lowes are twice as much and put out less light. I know, I have several of both. Plants are healthier and have better color under the LOA lights. Forget the lights labeled for plants. Cool whites work better IMHO. 4100k to 6500k