Yeah, good idea. xD;
Though, are you sure that you'll be able to buy HG/SS after buying platinum? If not, then I just suggest that you wait for and get either HG/SS. Platinum is just a 'tweaked' version of diamond and pearl with some really good additions. Buuut, it fails in comparison with HG/SS's EPICness. So, I'd suggest that you wait for HG/SS while playing diamond(if you aren't sure that you'll be able to buy HG/SS. If you're sure that you can save up for either HG or SS, then buying platinum won't hurt. Its all fine.) ;3
Though, are you sure that you'll be able to buy HG/SS after buying platinum? If not, then I just suggest that you wait for and get either HG/SS. Platinum is just a 'tweaked' version of diamond and pearl with some really good additions. Buuut, it fails in comparison with HG/SS's EPICness. So, I'd suggest that you wait for HG/SS while playing diamond(if you aren't sure that you'll be able to buy HG/SS. If you're sure that you can save up for either HG or SS, then buying platinum won't hurt. Its all fine.) ;3