I started off with an eBay special. After all the agro, I added up all the money I had put into making the kart right and found I could have ended up with a real decent package if I had saved up and looked around properly.
Moral of the story- a decent kart doesn’t come cheap.
The odd decent kart does occasionally find it’s way onto eBay. You will know the difference between a decent package and an eBay special as the asking price will be considerably different. A retirement sale is always good as you can often pick up lots of spares. Just be careful with the age of the frame with 125’s, the steel hardens over time.
Have you checked the classifieds on this site? Over in the UK we have ‘superkart.org.uk’ if there is anything worth buying in the UK that’s the best place to start.