If you have a valid business requirement for this data, this is (IMO) a dirty method of obtaining it.

In an ideal world, you'd ask the developers of the website so make available to you the source of the data so you can get it yourself.

If this is not viable, then i see no major problem with it. Infact the frequency of your "get" is entirely dependant on your requirement.

Again, If its a valid business requirement, why not get it from the source?

Update: My reply is from the POV of you being internal to the corporate site.