SEO is more than just keywords in domain names, you're buying into a long-term investment. His domain cost $2200 because it likely had lots of backlinks and page rank in Google, which is how he was able to get 600 orders (about $30k in revenue if my math is right) in the first year.
It's also the perfect combination of the two keywords with nothing else. You'll automatically be at a disadvantage.
But every large market typically has 1 leader and 1-3 other smaller companies who can survive. I doubt this is a large enough market where being #2 or #3 is going to be lucrative. You might as well find other niche premium vegetables. Like 1-800-Flowers and Harry & David (which the author mentioned) does...
https://www.wolfermans.com made a decent-sized business selling premium english muffins.