The price seems good, but the quality of those is 'questionable'. They just don't last very long. It's only a good deal while they still work.
The 1.5W fails with no obvious reason. The wire is not sunlight resistant.
The 5W seems to have layers seperate.
The 15W does both.

A better choice for the small sizes could be the VW panels. Mine all make more amps than they claim. They'll need a little weatherproofing. EBay, or the VW dealer may just give you a couple.

Spend a little more money for something in the 15 to 50W range.

For comparison purposes, I also looked at some Electronic Goldmine offerings.  Most of their offerings are 0.5VOC cells, so I'm not sure that they are a valid comparison.  However, the prices I'm getting are between $1.87 and $4.98 per amp.  I couldn't tell if they were blue or black, but most of them were chipped or rejects in some way (not a big deal for me).

A couple of others I sampled on Froogle (Sharp, C Crane, Kyocera, Envirolet -- all 12 VCC models, some blue and some black) ran from $53 to $179 per amp.
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The panels put out only about 36 watts but that's only been one test, I still need to mount them somewhere. They don't look to be too well sealed for weather but a little silicon would probably cure that.
I tested the charge controller and it seemed to work. The multi-voltage taps on the front worked but seemed to be a little low on their output voltage.
The two 12v cfl's put out a pretty fair amount of light at about 4.5 watts.
The frame they include is a little baffling.

Adding a battery gives a pretty fair system to goof around with if that's your plan and if you've got a coupon it may make the decision that much easier. I figure the bulbs are worth maybe $5 each, lets say $15 for the controller, add in the coupon and that brings the price down to around $5/watt even if they never produce more than 30 watts.

Example, if you have a 24V panel that makes 100 watts, that would be 4.16 amps and about $500.

If you have a panel that makes 4.16 amps, but your system is 12V instead of 24, the wattage would be 50 watts and about $200. Still the same amps, but different prices because they are sold by wattage, not amps.

Use wattage. . .

100 watts at 12V is 8.33A and 100 watts at 24 volts is 4.16 amps.  But it is still $500 no matter how you slice it.

In that case, my purchase candidates would be:

The Harbor Freight 45W panel -- $200
The Kyocera 50 W panel -- $233
The Sharp 185 W panel -- $880
The Kyocera 190 W panel -- $836

Although, I think I will go ahead and pick up a couple of the HF 1.5W, $9.99 units just for playing around...
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Still there may be some variability.  I am still trying to figure out the calculations.

For example, if you are feeding a 12V battery,

Shoot for VOC (Voltage Open Circuit) of around 18-20V for a 12V panel.
Short circuit Amps may or may not represent the number of amps you can push into your batteries.

Note, as you approach the VOC, the power (amps) drops significantly.

Thus, say you have a 12V panel, VOC=20V, With Short Circuit=2 Amps
I presume your Maximum Theoretical Watts is somewhere close to 2 Amps * 12V = 24 Watts (not 40 Watts using VOC in the calcs).

However,
If you are buying bare Cells...  they may be rated on the VOC and Short Circuit AMPS....   So, it may seem as if you have nearly double the power which really isn't there.