So I have about $500K in cash. I have yet to buy a car or kit. How do people usually do this? I only picked up free download ones and when forced to get a vehicle.
And how does the whole auction thing work?
make sure you are visiting forza rewards every week (resets on fridays), you get a variable amount of cash every week for every forza game based on your achieves/cars/etc
https://rewards.forzamotorsport.net/en-US
I get 275k/week from there and have tons of money. Like you I rarely buy cars, I bought the cars I own IRL and a few I wanted to check out but other than that I buy cars when I need to for an event, I buy cars during forzathon events when there are discounts on - like over the weekend there was 30% off on about a dozen offroad cars and I bought all the ones that were under 200k (i'm cheap still!). I still have 30+ cars I "own" via ultimate edition that I have yet to buy, I try to buy 2-3 a week but it always takes so long to go through setting up the paint job etc. Clicking on DLC cars from the main page lets you see which DLC cars you can get, they are "free" (once, after that you pay money) if they are part of a DLC pack you own.
Auctions are like ebay, you can search for specific cars or look at the rare/design/etc cars. place a bid or buyout, if you win you get the car. THe interface isn't that great and there tends to be heavy bid competition all times of the day on popular stuff so I rarely use it to be honest. The bottom right option lets you see cars that are horizon editions, which give you bonuses for xp/cash/skill/drift/etc and its useful to own one of each type of horizon event car, although tbh I rarely swap cars once I find a car I really, really like.
You can sell any car you own in the auction house, so stuff you win via spins or forzathon or whatever is a good way to raise money. It has minimum and maximum values so you can't really put it up at deep discounts or try to scam someone, although the max values tend to be insanely high i think.