Some of my hotlist HTF kits are:
1- Bandai 1/12 STP Granatelli Turbine Indycar. I had a mint one on the shelf for about 10 years, gathered lots of reference material to build it, then decided it was worth too much to put together. I sold it for just under $1000 about 5 years ago. They do pop up once in awhile.
2- Another Bandai rarity is the 1/12 1969 Corvette coupe. I have two of them, one carried from Australia. Neither is mint because Bandai, like so many large scale producers, didn't strengthen the center of the boxes. I have great plans for one of them, and the second will guarantee I have the parts to complete the project if I ever get to it. The remains will go up for sale.
3- Two of Entex's 1/8 race icons also hit the charts: the Porsche 934 Turbo Carrera and the McLaren M23 with Marlboro decals. Great kits, but mint ones are probably pushing $2000 now if you can find them. I have the Porsche in WIP, and gave up a McLaren for an offer I just couldn't refuse a few years back. I've never seen the 1/8 McLaren built or showed anywhere -- EVER.