When your laptops boots, press esc, and see if it recognized a fixed drive 0. if not, then you've come to the right conclusion. If it does say fixed drive 0 = Toshiba m whatever , then its definately twilight zone.
1. ) If you decide to replace the Hard Drive, then there are two places I would go.
One would be the gateway site, because they would probably provide somewhat of a warranty on the drive if you bought it from them.
The other would probably be eBay. The reason i say ebay is that it may be cheaper.
2.) There may be a wholesaler of laptop Hard Drives. To be honest, never heard of one.
3. ) Any data on there that was mission-critical or what-not?
Did it spark or anything when the tea was applied?