GoDaddy’s domain auction space serves as a “marketplace” for buyers and sellers to get together and make deals. When a domain expires, it typically goes right back to the registry. If it’s a valuable domain name, however, registrars will try to sell it through auction, and buyers are always eager to capitalize on potential deals. Participating in a domain auction can be a nuanced business, so take a look at our Auctions FAQ page for more details on the process.
Buying a website is a risky job especially if the investment is big. My first experience was a big fail. So after some time spent on Flippa I found out about a site called Safe Site Buying which I heard that was created by super sellers from flippa and got a coupon code "flippa50" which was supposed to give me a huge 50% discount. This deal looked pretty good to me so I tried it. They provided me with a full report, 20 pages long and with their own subjective opinion. They were very helpful. When you want to spend more than $2-3000 on a website this service is a must if you ask me.
The second option requires a bit more time and effort than a 301 redirect. You could do a mini overhaul of the site and turn it into a microsite for your main domain. This option is good for exact-match domains for your targeted keyword, and there are other reasons for going the microsite route that Rand's highlighted in his post about root domains, subdomains, subfolders and microsites. This strategy also works better if the old domain has decent rankings for the keywords you're targeting.
That said, my recommended budget for beginners would be $500+. Using this budget you could buy a bunch of high-potential $10 domain names, expired/dropped domain names or a mix of both. It’s very important to invest only what you can afford to lose and treat this as a side hustle till you get the momentum going. As you gain experience, industry expertise and some sales under your belt, you can then consider slowly growing your business into a full-time gig.