Bob has many good points & recommendations in his response! I have taken hummer photographs with multiple flash units off & on for years dating back to that 4-letter word, FILM! LOL Spent a fortune too getting decent hummer shots.
Don't rule out the possibility of shooting remotely. The last few years my hummers haven't cooperated as they have picked elsewhere as a primary food source and come to our feeders too irregularly to try getting some shots so I've instead used my SU-800 & 3, SB-800s to capture birds in flight going to our regular bird feeders.
I just use a Sigma 150mm APO macro lens and prefocus manually at a spot close to the feeder. I modified an aftermarket wired flash so that I can sit up to 45ft away or so. Hummers are not shy and lots of backyard birds aren't either once they get used to you. I usually sit about 10 feet away.
I just bought a D5100 and have also bought 3-4 new remote options so that I don't have to go wired anymore and will try them out this spring.
Here is an image using my equipment & technique:
FYI, I've also done lots of butterfly photography. I even raised several varieties to get specimens with flawless wings. I can offer lots of advice here if you are interested. Not bragging, just offering help!