I used to collect full series' when I was a kid. Now I just look for cool Japanese or classic cars.
I must say, however, that this fucking trend of capitalizing on HotWheels collectors is fucking disgusting. I hate it when I go to a local Target to look for the Kaido House Z and there are absolutely ZERO...then I go on IG and see that some middle-aged man hounded the kid in the toy department to bring out the boxes so he could raid them for all of the cool cars. Buys 20 Datsuns for ~$30 and then sells them for 5 times their original price. Total crock of shit.
Before you say that's just the 'game' or 'the early bird gets the worm' I'd like to let you know I disagree. I'm not religious but I'm pretty sure greed is one of the Seven Deadly Sins. That's all this is: greed. The same can be said about the guys that buy Japanese parts from Jesse Streeter and then turn them for a huge profit.
I finally found a Redline '72 Skyline at Autozone of all places.
I ended up finding two 180SXs in the wild (NEX and a random CVS) after I purchased one on eBay for $5