Just to follow up, I've landed complete Turbochips for Victory Run and Final Lap Twin now. I've played them both briefly and they both seem to have enough going on that I would need to sit down with them to get a thorough experience out of them. I like that, plus I can play Final Lap Twin two player if anybody ever wants to.
I haven't even seen Outrun PCE on ebay since I started looking last year, I hope it doesn't go for too much when it does show up. I've almost bit the bullet on Power Drift a couple of times now, but it went for a buck or two more than I want to spend on it. I'm eyeing Racing Spirits too, that one looks great.
-edit-
I just finished about an hour of quest mode in Final Lap Twin. I'm really enjoying it so far. I like how your dad gives you $300 every time you lose. Also, I saw a video review of this before I bought it that said the jumps didn't do anything. The jumps speed the car up and are the only way aside from turbo fuel that can get the car to break top speed, but it actually stays at a higher speed with the jumps. I bought all of the upgrades from the first town and wrote down the password. Now it's time to see if I can beat the first champ, that dude just took off the first time I raced him!