Great idea - even if it is being done already

When you have (what you think is) a “great idea” – what do you do? I get this false positive often, so I write a quick summary and maybe a sketch in one of my many notebooks (yes, with a pen) or, if I’m online, I add it to my perpetual JR-ideas document (yes, of course it's a google doc).
Sometimes, I actually believe I have an original, great idea and I begin to consider plans to get it from concept to market. Many times, the idea is probably crap, and I know it, but I write it down anyway (there's an analogy here with cow-produced fertilizer - where maybe this idea can help another better idea grow... so maybe that's why I keep it). In either case, the step I recently realized that I avoid for a while is the obvious research step - the online search (yes, of course that online search) to see whether and how this idea has been done before...

I'm pretty sure I avoid the search for 2 reasons:

1 - If I find other examples of this idea too soon, it might ruin my creative process and sub-consciously guide me towards the pre-existing designs... I'd be influenced and "my" idea might not get a fair shot at becoming unique or innovative.

2 - I'm never quite sure whether finding examples of the idea is better or worse than NOT finding examples... This is actually the root concept I wanted to make in this post (it always takes me a while to get there, doesn't it?)...

So if I find no results in my search - that is, no examples of products implementing this idea - I can look at that optimistically ("yay! I'm first! I knew this was a great idea!"), or, pessimistically ("...of course nobody's doing this - I knew it was a bad idea.. they probably tried and failed or did the research and found no market or no margin")...

If I do find results in my search - examples of this "unique" idea - again, the optimist says "see? This IS a great idea! People are already spending money in this area!", while the pessimist says (in their best Eeyore voice) "hmmm... too late... again".

The other day, I had one of these self-proclaimed "great ideas"... one which I actually told a few people just to get their reaction. My personal litmus test passed, which is "I would buy one of these!"

The Idea: Crank-powered Cell Phone Charger

You've seen those emergency radios, right? with the crank on the side so you don't need batteries... well... why not power a cell phone that way? We all have "emergencies" where we have no power in our cell phone, but urgently need to call home to see if we should be picking up milk or pizza ;)

Was I right? Is this a great idea?

Of course it’s a great idea (is it?) – that’s why it’s been done! (does that make it a great idea?)
When I finally took the obvious step of searching for such a product, I found more than a few – including the Sidewinder, which was exactly what I envisioned when I wrote this (ahem...) totally original idea in my ideas list.
In fact, CNet, Gizmodo and Engadget all reviewed such devices (ok... Engadget's was a review of a different kind of cell phone charger which probably had no predecessors when the dude pictured did his search for "hamster-powered cell-phone charger"), but the Gadgeteer reviewed the SideWinder as far back as September, 2003 ;)

So - my conclusion is, it's ok to take a bit of time developing an idea before even looking at the market... I think it does help the creative process... but when those 4 minutes of innovation are over (ok, maybe 40), I'll do the search! Even if the results (or lack of) leave me confused and optimistic (or is that pessimistic?), at least I'll know whether I can just buy one - rather than designing, developing, producing, testing , fixing and producing again, just so I can have one myself.