Nobody asked this yet?
Anyway, guys, I know one place where you can get Free Heart Scales, everyday. No, I don't mean the Driftveil Lady who wants to see some TMs in return for a Heart Scale.
In the housing/ residential part, i.e., in this part of Humilau City,
Use the Dowsing MCHN to find a Heart Scale. Here's the good part: You can get one everyday for free. In the same spot.
Source: Personal Experience :)
Have fun...
Now, that apart, do you know any other place for Heart Scales?