I'd say 7500 is an alright score. Though I'm not the best judge of scores since I pretty much played it for a week straight. Though the key to getting an incredibly high score is to try and maintain your combo because it increases the score exponentially every time it goes up.
If you look in the comments on the actual game page, one of my friends got 5,200,000 just by getting a combo of like 70 or something crazy like that!