In thinking off of the top of my head about your proposal, I'm in at a bit more than $300, but a functional system might be something like this.  you might be able to rig a 30 watt panel (I happened to see a 30 Watt Panel at Sunelectric Miami for $125 plus shipping but check all on-line vendors) A trace C12 charge controller or something similar with charge and integrated low voltage disconnect for $75 or less from EBAY, a marine deep cycle battery for about $80 (not very good, but you don't have enough current coming in at 30 watts for golf cart batteries which would be a step up and you budget precludes other, more expensive batteries), a small 12V 400 Watt inverter for $25 like one I saw at Amazon.com for those items for which you cannot get 12 volt auto style chargers for, and about 25 bucks for cigarette lighter sockets from an auto parts store and wiring, also I would probably pick up a 12V to 5V USB style cigarette plug adapter if I had devices that charged from USB. I don't like the durability of cigarette lighter sockets, so I would probably hard wire through switches the items which would not need to be mobile, In my case, I scalp old switches and stuff from old electronics.  By the way, I have no affiliation with any of the vendors mentioned, they are just items that I have seen, and anyway, these are just some ideas.

This would give you a basic system with a 12V DC capacity to charge items from 12V, and a small 120VAC component for things that can charge from it, or in case of a power outage to run a small appliance or tool.  

Wet Feet?
The HF kit, with mounting brackets and a pair of 12VDC CFLs, on sale, with a 15% off coupon, $150.
Big giant yellow wally-world deep cycle, $100.
SG-4 to replace the HF controller, before it ruins the battery, $30.
"Odds-n-Ends", $25 to $50?

Throw in a Vector 400W inverter from Pep-Boys, on sale and with rebates, $30, sometimes $25.

That would be usable power.  Small but usable.

While there, also look for a little 100 - 150 watter inverter, will be one that you can plug into a cigarette lighter. shouldn't be more than $30, I paid 19 on sale.

Also, look at ALL of the chargers ( walwarts) and find the wattage levels most so as a level of 120Vac , multiply this by 10 if they do. add them all up and see if the total in above the 100 - 150 watter inverter if so find a bigger one to handle the total but about 20% more.

Once you have the Panels, find a nice unshaded place that you can set it up connect it the way the instructions say to, connect the battery to the controller, the one that came with the kit ( for now) let it set in the sun for a few days, unless you've fully charged the battery already. You don't need to have the controller turned on to charge the battery , plus the new ones have a little button to turn off the display. Once the display shows 12.8 volts or above, plug the inverter into the cigarette outlet and plug a power strip into the inverter and let the items charge.

NOTE: This is one of many simple ways to do this without a full load of money and gives back almost instant rewards. Which will go a long way to showing even the kids how neat this stuff is. You could even make note that having the walwarts plugged into this and not into the house that's 24/7 power you're not waisting.
There much more effiecent ways, but this should be one of the quickest and eaiser ways.
Then if you don't mind come back with pics and let us know how it's doing.
There are people on here that can steer you to the correct devices if you decide to go larger and can help decide. Only things needed are how much more you want to do and what the power requirements are
Hope this helps;
Bruce S