I would say just go for it! You can't know how well or even if something will sell unless you put it out there and try to sell it. It could end up costing you money if people aren't buying OR you could make a lot of money with it but there's only one way to find out.
I would advise to make games firstly because of a love of games and only think about the money secondly because that's staying true to the artform. Which, contrary to certain ignorant critics, video games are an art form!
If you just want to make money then don't even bother making good games. If you look at what makes money these days you'll find uninspired crappy games like Angry Birds. So the key to making money is making a crappy unoriginal game and somehow getting it popular.
WilkinGames
Just checked out Alien Splatter. Keep up the good work!
SinclairStrange
Thanks! :). I'm glad you liked the game.