Personally, I would stick with DVD for a few reasons:
1) Its considerably cheaper, not to mention the discs are cheaper.
2) More people have DVD than BlueRay... if you need to distribute a disc, others will have a better chance of being able to use it.
3) If you are looking into getting one for movies, its pointless if you dont have a really good TV. If your TV isnt high quality, the video playback wont be either, no matter what device you are using.
4) Its expensive! Especially for a good fast one! Go with technology thats already established and cheap.
If you have the money to spend, and if you think that distribution wont be a problem whatsoever, and if its being used for video and you have a good high definition TV, then go with BlueRay...
If DVD's will still work out for you, why not go with them? They work fine, and if you need to backup large files, you can always spread them across multiple discs.
But, either way, a company is going to make money somewhere...